| [175] | 1 | subroutine n_ethane(ngrid,nq,nbin, |
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| 2 | * dt,pl,tl,aerad, |
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| 3 | * q,qprime) |
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| 4 | |
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| 5 | implicit none |
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| 6 | #include "dimensions.h" |
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| 7 | #include "microtab.h" |
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| 8 | #include "varmuphy.h" |
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| 9 | |
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| 10 | c Arguments |
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| 11 | c --------- |
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| 12 | |
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| 13 | integer ngrid,nq,nbin |
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| 14 | |
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| 15 | REAL dt ! physical time step (s) |
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| 16 | REAL pl(ngrid,nz) ! pressure at each level (mbar) |
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| 17 | REAL tl(ngrid,nz) ! temperature at each level (K) |
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| 18 | REAL aerad(nbin) ! Radius array |
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| 19 | |
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| 20 | c Tracers : |
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| 21 | REAL q(ngrid,nz,nq) ! tracer (kg/kg) |
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| 22 | REAL qprime(ngrid,nz,nbin) ! tracer (kg/kg) |
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| 23 | |
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| 24 | |
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| 25 | c Local variables |
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| 26 | c --------------- |
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| 27 | |
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| 28 | integer ntyp |
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| 29 | parameter (ntyp=3) |
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| 30 | |
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| 31 | real n_aer(nz,nbin,ntyp) |
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| 32 | real c2h6vap(nz) |
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| 33 | |
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| 34 | integer itrac |
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| 35 | integer ig,i,j,k,l,n ! Loop integers |
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| 36 | integer ilay,iq |
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| 37 | |
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| 38 | c Treatment |
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| 39 | c --------- |
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| 40 | |
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| 41 | DO ig = 1 , NGRID |
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| 42 | |
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| 43 | c Set up the aerosol array |
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| 44 | do j = 1, ntyp |
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| 45 | do k = 1, nbin |
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| 46 | itrac = (j-1) * nbin + k |
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| 47 | do l = 1, nz |
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| 48 | n_aer(l,k,j) = max(q(ig,l,itrac),0.) |
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| 49 | enddo |
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| 50 | enddo |
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| 51 | enddo |
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| 52 | |
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| 53 | c Set up the methane vapor array |
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| 54 | do l = 1, nz |
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| 55 | c2h6vap(l) = q(ig,l,nq) |
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| 56 | enddo |
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| 57 | |
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| 58 | call nucleacond2(ngrid,nbin,dt,ig,pl,tl,aerad, |
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| 59 | & n_aer,qprime,c2h6vap) |
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| 60 | |
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| 61 | c Update q arrays |
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| 62 | do j = 1, ntyp |
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| 63 | do k = 1, nbin |
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| 64 | itrac = (j-1) * nbin + k |
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| 65 | do l = 1, nz |
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| 66 | q(ig,l,itrac) = n_aer(l,k,j) |
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| 67 | enddo |
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| 68 | enddo |
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| 69 | enddo |
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| 70 | |
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| 71 | c Update methane vapor array |
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| 72 | do l = 1, nz |
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| 73 | q(ig,l,nq) = c2h6vap(l) |
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| 74 | |
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| 75 | c if(q(ig,l,nq).le.0.) print*,'in nuc2h6',ig,l, q(ig,l,nq) |
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| 76 | |
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| 77 | enddo |
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| 78 | |
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| 79 | ENDDO |
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| 80 | |
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| 81 | return |
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| 82 | END |
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| 83 | |
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| 84 | **************************************************************** |
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| 85 | subroutine nucleacond2(ngrid,nbin,dt,ig, |
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| 86 | * pl,tl,aerad,n_aer,qprime,c2h6vap) |
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| 87 | * * |
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| 88 | * This routine updates species concentrations due * |
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| 89 | * to both nucleation and condensation-induced variations. * |
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| 90 | * Gain and loss rates associated to each one of these * |
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| 91 | * processes are computed separately in other routines. * |
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| 92 | * * |
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| 93 | **************************************************************** |
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| 94 | |
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| 95 | implicit none |
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| 96 | #include "dimensions.h" |
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| 97 | #include "microtab.h" |
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| 98 | #include "varmuphy.h" |
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| 99 | |
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| 100 | |
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| 101 | integer ng,nalt |
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| 102 | parameter(ng=1,nalt=llm) |
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| 103 | |
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| 104 | real lv |
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| 105 | |
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| 106 | * dejà évalué dans n_methane ! |
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| 107 | REAL x1(nalt) |
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| 108 | REAL x2(nalt) |
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| 109 | REAL x3(nalt) |
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| 110 | REAL icefrac(nalt) |
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| 111 | REAL pmixch4(nalt) |
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| 112 | REAL pmixc2h6(nalt) |
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| 113 | REAL pmixn2(nalt) |
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| 114 | |
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| 115 | common/lheat/lv |
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| 116 | common/mixing/x1,x2,x3,icefrac, |
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| 117 | & pmixch4,pmixc2h6,pmixn2 |
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| 118 | |
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| 119 | |
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| 120 | |
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| 121 | c Arguments |
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| 122 | c --------- |
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| 123 | |
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| 124 | integer ngrid,nbin |
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| 125 | integer ig |
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| 126 | integer ntyp |
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| 127 | parameter (ntyp=3) |
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| 128 | |
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| 129 | real dt ! Global time step |
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| 130 | real pl(ngrid,nz),tl(ngrid,nz) |
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| 131 | real aerad(nbin) |
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| 132 | real c2h6vap(nz) ! Methane vapor mass mixing ratio (kg/m3) |
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| 133 | real c2h6vap_old |
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| 134 | real n_aer(nz,nbin,ntyp) ! number concentrations of particle/each size bin |
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| 135 | real qprime(ngrid,nz,nbin) ! tracer (kg/kg) |
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| 136 | REAL total1(nz),total11(nz),total2(nz),total22(nz) |
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| 137 | REAL dmsm,mtot |
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| 138 | |
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| 139 | |
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| 140 | |
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| 141 | |
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| 142 | |
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| 143 | c Local |
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| 144 | c ----- |
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| 145 | |
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| 146 | integer i,j,k,l,n,iindice,iselec |
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| 147 | |
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| 148 | real dQc ! Amount of condensed methane (kg/m3) during timestep |
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| 149 | real*8 sat_ratio ! Methane saturation ratio over liquid |
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| 150 | real*8 sat_ratmix ! Methane saturation ratio over liquid |
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| 151 | real*8 pc2h6 ! Methane partial pressure (Pa) |
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| 152 | real qsat ! Methane mass mixing ratio at saturation (kg/kg of air) |
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| 153 | real qsatmix ! Methane mass mixing ratio at saturation (kg/kg of air) |
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| 154 | real*8 rate(nbin) ! Heterogeneous Nucleation rate (s-1) |
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| 155 | real*8 elim |
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| 156 | |
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| 157 | real nsav(nbin,ntyp) |
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| 158 | real dn(nbin,ntyp) |
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| 159 | real rad(nbin) ! Radius of droplets in each size bin |
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| 160 | real*8 gr(nbin) ! Growth rate in each bin |
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| 161 | real radius ! Radius of droplets after growth |
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| 162 | real Qs ! Mass of condensate required to reach saturation |
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| 163 | real newsat |
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| 164 | real vol(nbin) |
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| 165 | |
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| 166 | real press |
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| 167 | real sig2,temp,seq(nbin) |
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| 168 | real Ctot,up,dwn,newvap,gltot |
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| 169 | |
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| 170 | real temp0,temp1,temp2,last_temp |
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| 171 | real qsat1,sat_ratio1,tempf(0:10),sat_ratiof(0:10) |
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| 172 | real rho_a,cap |
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| 173 | real tempref |
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| 174 | real xtime,xtime_prime |
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| 175 | |
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| 176 | |
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| 177 | |
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| 178 | c Variables for latent heat release |
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| 179 | real lw,cpp |
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| 180 | data lw / 581.e+3/ |
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| 181 | c data cpp/1044./ |
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| 182 | data cpp/1050./ ! pour etre cohérent avec le reste... |
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| 183 | save lw,cpp |
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| 184 | |
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| 185 | |
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| 186 | c Treatment |
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| 187 | c --------- |
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| 188 | do i = 1, nbin |
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| 189 | vol(i) = 4./3. * pi * aerad(i)**3. |
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| 190 | enddo |
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| 191 | |
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| 192 | do l = 1, nz |
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| 193 | total1(l)=0. !solide |
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| 194 | do k = 1, nbin |
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| 195 | total1(l)=total1(l)+n_aer(l,k,2)*rhoi_c2h6 |
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| 196 | enddo |
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| 197 | total2(l)=c2h6vap(l) |
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| 198 | enddo |
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| 199 | |
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| 200 | |
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| 201 | c Start loop over heights |
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| 202 | DO 100 l = 1, nz |
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| 203 | |
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| 204 | iindice=0 ! mettre l'indice à 0 |
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| 205 | |
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| 206 | temp = tl(ig,l) |
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| 207 | press = pl(ig,l) |
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| 208 | tempref=temp |
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| 209 | |
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| 210 | c Save the values of the particle arrays before condensation |
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| 211 | do j = 1, ntyp |
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| 212 | do i = 1, nbin |
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| 213 | nsav(i,j) = n_aer(l,i,j) |
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| 214 | enddo |
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| 215 | enddo |
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| 216 | |
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| 217 | |
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| 218 | 99 continue |
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| 219 | |
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| 220 | |
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| 221 | call c2h6sat(temp,press,qsat) |
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| 222 | qsatmix=qsat |
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| 223 | |
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| 224 | c quantité pmixc2h6(l) déjà calculé dans cnuages.F et passé dans un common |
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| 225 | c qsat=pmixc2h6(l)*30.0 / (28.0*p) |
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| 226 | c qsatmix=pmixc2h6(l)*30.0 / (28.0*p) |
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| 227 | |
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| 228 | c Get the partial presure of methane vapor and its saturation ratio |
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| 229 | pc2h6 = c2h6vap(l) * (Mn2/Mc2h6) * press |
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| 230 | sat_ratio = c2h6vap(l) / qsat |
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| 231 | sat_ratmix = c2h6vap(l) / qsatmix |
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| 232 | |
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| 233 | c Get the rates of nucleation |
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| 234 | call nuclea2(nbin,aerad,pc2h6,temp,sat_ratio,rate) |
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| 235 | |
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| 236 | c Get the growth rates of condensation/sublimation |
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| 237 | up = c2h6vap(l) |
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| 238 | dwn = 1. |
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| 239 | Ctot = c2h6vap(l) |
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| 240 | DO i = 1, nbin |
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| 241 | |
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| 242 | if (n_aer(l,i,3).eq.0) then |
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| 243 | rad(i) = aerad(i) |
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| 244 | else |
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| 245 | rad(i) = ((n_aer(l,i,2)/n_aer(l,i,3) + |
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| 246 | & qprime(ig,l,i)/n_aer(l,i,3) |
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| 247 | & +vol(i))*0.75/pi)**(1./3.) |
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| 248 | endif |
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| 249 | |
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| 250 | |
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| 251 | * Equilibrium saturation ratio (due to curvature effect) |
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| 252 | seq(i) = exp( 2.*sig2(temp)*Mc2h6 /(rhoi_c2h6*rgp*temp*rad(i))) |
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| 253 | |
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| 254 | call growthrate2(dt,temp,press,pc2h6, |
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| 255 | & sat_ratmix,seq(i),rad(i),gr(i)) |
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| 256 | up = up + dt * gr(i) * 4. * pi * rhoi_c2h6 * rad(i) * seq(i) |
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| 257 | * * nsav(i,3) |
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| 258 | dwn= dwn+ dt * gr(i) * 4. * pi * rhoi_c2h6 * rad(i) / qsat |
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| 259 | * * nsav(i,3) |
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| 260 | Ctot= Ctot + rhoi_c2h6 * nsav(i,2) |
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| 261 | |
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| 262 | ENDDO |
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| 263 | |
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| 264 | newvap = min(up/dwn,Ctot) |
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| 265 | newvap = max(newvap,0.) |
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| 266 | |
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| 267 | gltot = 0. |
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| 268 | DO i = 1, nbin |
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| 269 | gr(i) = gr(i) * ( newvap/qsat - seq(i) ) |
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| 270 | if(nsav(i,2).le.0. .and. gr(i).le.0.) then |
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| 271 | n_aer(l,i,2) = 0. |
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| 272 | else |
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| 273 | n_aer(l,i,2) = nsav(i,2) + dt * gr(i) * 4. * pi * rad(i) |
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| 274 | * * n_aer(l,i,3) |
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| 275 | if (n_aer(l,i,2).le.0.) then |
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| 276 | n_aer(l,i,1) = n_aer(l,i,1) + n_aer(l,i,3) |
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| 277 | n_aer(l,i,2) = 0. |
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| 278 | n_aer(l,i,3) = 0. |
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| 279 | endif |
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| 280 | gltot=n_aer(l,i,2)*rhoi_c2h6+gltot |
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| 281 | endif |
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| 282 | |
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| 283 | ENDDO |
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| 284 | |
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| 285 | c Determine the mass of exchanged methane |
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| 286 | |
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| 287 | dQc = 0. |
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| 288 | DO i = 1, nbin |
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| 289 | dQc = dQc - rhoi_c2h6 * ( n_aer(l,i,2) - nsav(i,2) ) |
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| 290 | ENDDO |
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| 291 | |
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| 292 | c Update the methane vapor mixing ratio implied by |
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| 293 | c the cond/eva processes. |
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| 294 | |
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| 295 | |
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| 296 | c Arrays resetted to their initial value before condensation |
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| 297 | do j = 1, ntyp |
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| 298 | do i = 1, nbin |
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| 299 | dn(i,j) = n_aer(l,i,j) - nsav(i,j) |
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| 300 | n_aer(l,i,j) = nsav(i,j) |
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| 301 | enddo |
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| 302 | enddo |
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| 303 | |
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| 304 | c Update the c arrays. |
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| 305 | c nucleation & cond/eva tendencies added together. |
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| 306 | |
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| 307 | do i=1,nbin |
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| 308 | elim = dt * rate(i) |
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| 309 | n_aer(l,i,1) = n_aer(l,i,1) / (1.+elim) |
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| 310 | n_aer(l,i,3) = n_aer(l,i,3) + elim * n_aer(l,i,1) + dn(i,3) |
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| 311 | n_aer(l,i,1) = n_aer(l,i,1) + dn(i,1) |
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| 312 | n_aer(l,i,2) = n_aer(l,i,2) + dn(i,2) |
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| 313 | if(n_aer(l,i,2).lt.0.) n_aer(l,i,2)=0. |
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| 314 | enddo |
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| 315 | |
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| 316 | dQc = 0. |
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| 317 | DO i = 1, nbin |
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| 318 | dQc = dQc - rhoi_c2h6 * ( n_aer(l,i,2) - nsav(i,2) ) |
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| 319 | ENDDO |
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| 320 | |
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| 321 | |
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| 322 | c2h6vap(l) = c2h6vap(l) + dQc |
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| 323 | |
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| 324 | 100 CONTINUE |
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| 325 | |
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| 326 | do l = 1, nz |
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| 327 | total11(l)=0. |
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| 328 | do k = 1, nbin |
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| 329 | total11(l)=total11(l)+n_aer(l,k,2)*rhoi_c2h6 |
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| 330 | enddo |
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| 331 | total22(l)=c2h6vap(l) |
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| 332 | enddo |
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| 333 | |
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| 334 | return |
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| 335 | end |
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| 336 | |
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| 337 | |
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| 338 | ******************************************************* |
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| 339 | * * |
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| 340 | subroutine nuclea2(nbin,aerad,pc2h6,temp,sat,nucrate) |
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| 341 | * This subroutine computes the nucleation rate * |
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| 342 | * as given in Pruppacher & Klett (1978) in the * |
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| 343 | * case of water ice forming on a solid substrate. * |
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| 344 | * Definition refined by Keese (jgr,1989) * |
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| 345 | * * |
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| 346 | ******************************************************* |
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| 347 | |
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| 348 | implicit none |
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| 349 | #include "dimensions.h" |
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| 350 | #include "microtab.h" |
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| 351 | #include "varmuphy.h" |
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| 352 | |
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| 353 | integer nbin |
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| 354 | real aerad(nbin) |
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| 355 | |
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| 356 | real*8 nucrate(nbin) |
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| 357 | real*8 pc2h6 |
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| 358 | real temp |
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| 359 | real*8 sat |
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| 360 | |
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| 361 | integer l,i |
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| 362 | real*8 nc2h6 |
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| 363 | real sig2 ! Water-ice/air surface tension (N.m) |
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| 364 | real*8 rstar ! Radius of the critical germ (m) |
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| 365 | real*8 gstar ! # of molecules forming a critical embryo |
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| 366 | real*8 x ! Ratio rstar/radius of the nucleating dust particle |
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| 367 | real fistar ! Activation energy required to form a critical embryo (J) |
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| 368 | real*8 zeldov ! Zeldovitch factor (no dim) |
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| 369 | real*8 fshape2 ! function defined at the end of the file |
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| 370 | real*8 deltaf |
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| 371 | |
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| 372 | real nus |
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| 373 | data nus/1.e+13/ ! Jump frequency of a molecule (s-1) |
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| 374 | real m0 |
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| 375 | data m0/4.983e-26/ ! Weight of a methane molecule (kg) |
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| 376 | real vo1 |
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| 377 | c data vo1/9.094e-29/ |
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| 378 | data vo1/5.4746e-5/ ! Volume of 1 mole |
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| 379 | real desorp |
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| 380 | data desorp/0.288e-19/ ! Activation energy for desorption of water on a dust-like substrate (J/molecule) |
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| 381 | real surfdif |
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| 382 | data surfdif/0.288e-20/! Estimated activation energy for surface diffusion of water molecules (J/molecule) |
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| 383 | |
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| 384 | IF (sat .GT. 1.) then ! minimum condition to activate nucleation |
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| 385 | |
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| 386 | nc2h6 = pc2h6 / kbz / temp |
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| 387 | rstar = 2. * sig2(temp) * vo1 / (rgp*temp*log(sat)) |
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| 388 | gstar = 4. * nav * pi * (rstar**3) / (3.*vo1) |
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| 389 | c Loop over size bins |
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| 390 | do i=1,nbin |
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| 391 | x = aerad(i) / rstar |
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| 392 | x = aerad(imono) / rstar ! r(5)=monomere |
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| 393 | fistar = (4./3.*pi) * sig2(temp) * (rstar**2.) |
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| 394 | & *fshape2(mtetac2h6,x) |
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| 395 | deltaf = min( max((2.*desorp-surfdif-fistar)/(kbz*temp) |
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| 396 | & , -100.), 100.) |
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| 397 | if (deltaf.eq.-100.) then |
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| 398 | nucrate(i) = 0. |
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| 399 | else |
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| 400 | zeldov = sqrt ( fistar / (3.*pi*kbz*temp*(gstar**2.)) ) |
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| 401 | nucrate(i) = zeldov * kbz* temp * rstar**2. |
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| 402 | & * 4. * pi * ( nc2h6*aerad(i) )**2. |
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| 403 | & / ( fshape2(mtetac2h6,x) * nus * m0 ) |
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| 404 | & * dexp(deltaf) |
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| 405 | if(i.gt.imono) nucrate(i)= zeldov * kbz* temp * rstar**2. |
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| 406 | & * 4. * pi * vrat_e**(i-imono)*(nc2h6*aerad(imono) )**2. |
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| 407 | & / (fshape2(mtetac2h6,x) * nus * m0 ) |
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| 408 | & * dexp(deltaf) |
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| 409 | |
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| 410 | endif |
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| 411 | enddo |
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| 412 | ELSE |
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| 413 | do i=1,nbin |
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| 414 | nucrate(i) = 0. |
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| 415 | enddo |
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| 416 | |
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| 417 | ENDIF |
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| 418 | |
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| 419 | return |
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| 420 | end |
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| 421 | |
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| 422 | ****************************************************************** |
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| 423 | subroutine c2h6sat(t,p,qsat) |
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| 424 | * * |
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| 425 | * cette fonction calcule la pression de vapeur saturante de l' * |
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| 426 | * ethane a une altitude donnee z par Reid et al., p657 * |
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| 427 | * * |
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| 428 | * Compatible avec Barth et al., dans l'intervalle 30-90K * |
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| 429 | * * |
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| 430 | * * |
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| 431 | ****************************************************************** |
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| 432 | |
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| 433 | real rgp |
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| 434 | data rgp/8.3143/ |
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| 435 | |
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| 436 | * declaration des variables internes |
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| 437 | * ---------------------------------- |
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| 438 | |
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| 439 | real qsat,t,p |
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| 440 | |
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| 441 | c qsat=10.01-1085.0/(t-0.561) |
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| 442 | c qsat=10.**qsat/760.*1.e5 |
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| 443 | |
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| 444 | |
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| 445 | a=-6.34307 |
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| 446 | b=1.011630 |
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| 447 | c=-1.19116 |
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| 448 | d=-2.03539 |
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| 449 | pc=48.8*1.e5 |
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| 450 | tc=305.4 |
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| 451 | |
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| 452 | x=(1.-t/tc) |
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| 453 | if(x.gt. 0.) qsat=(1-x)**(-1)*(a*x+b*x**1.5+c*x**3.+d*x**6.) |
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| 454 | if(x.le. 0.) qsat=a*x/abs(1.-x) ! approx pour t > tc |
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| 455 | qsat=pc*exp(qsat) |
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| 456 | |
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| 457 | qsat=qsat* 30.0 / (28.0*p) ! kg/kg |
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| 458 | |
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| 459 | return |
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| 460 | end |
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| 461 | |
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| 462 | c======================================================================= |
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| 463 | subroutine growthrate2(timestep,temp,press,pc2h6,sat,seq,r,Cste) |
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| 464 | c |
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| 465 | c Determination of the droplet growth rate |
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| 466 | c |
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| 467 | c======================================================================= |
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| 468 | |
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| 469 | IMPLICIT NONE |
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| 470 | #include "dimensions.h" |
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| 471 | #include "microtab.h" |
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| 472 | #include "varmuphy.h" |
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| 473 | |
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| 474 | c----------------------------------------------------------------------- |
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| 475 | C DECLARATIONS: |
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| 476 | c ------------- |
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| 477 | |
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| 478 | common/lheat/Lv |
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| 479 | |
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| 480 | |
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| 481 | c |
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| 482 | c arguments: |
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| 483 | c ---------- |
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| 484 | |
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| 485 | REAL timestep |
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| 486 | REAL temp ! temperature in the middle of the layer (K) |
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| 487 | REAL press ! pressure in the middle of the layer (K) |
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| 488 | REAL*8 pc2h6 ! Methane vapor partial pressure (Pa) |
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| 489 | REAL*8 sat ! saturation ratio |
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| 490 | REAL r ! crystal radius before condensation (m) |
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| 491 | REAL seq ! Equilibrium saturation ratio |
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| 492 | |
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| 493 | c local: |
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| 494 | c ------ |
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| 495 | |
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| 496 | REAL psat |
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| 497 | REAL moln2,molc2h6 |
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| 498 | REAL To,tc2h6,wc2h6 ! Reid et al., (eq 7-9.4 + Appendix compound [168]) |
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| 499 | REAL fte |
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| 500 | |
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| 501 | c Effective gas molecular radius (m) |
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| 502 | data moln2/1.75e-10/ ! N2 |
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| 503 | c Effective gas molecular radius (m) |
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| 504 | data molc2h6/2.22e-10/ ! C2H6 |
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| 505 | c Temperature critique + omega |
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| 506 | data tc2h6/305.4/ |
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| 507 | data wc2h6/9.9e-2/ |
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| 508 | |
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| 509 | REAL k,Lv |
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| 510 | REAL knudsen ! Knudsen number (gas mean free path/particle radius) |
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| 511 | REAL a,Dv,lambda,Rk,Rd ! Intermediate computations for growth rate |
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| 512 | REAL*8 Cste |
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| 513 | |
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| 514 | c----------------------------------------------------------------------- |
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| 515 | c Ice particle growth rate by diffusion/impegement of molecules |
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| 516 | c r.dr/dt = (S-Seq) / (Seq*Rk+Rd) |
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| 517 | c with r the crystal radius, Rk and Rd the resistances due to |
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| 518 | c latent heat release and to vapor diffusion respectively |
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| 519 | c----------------------------------------------------------------------- |
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| 520 | |
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| 521 | psat = pc2h6 / sat |
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| 522 | |
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| 523 | c - Thermal conductibility of N2 |
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| 524 | |
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| 525 | k = ( 2.857e-2 * temp - 0.5428 ) * 4.184e-3 |
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| 526 | |
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| 527 | |
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| 528 | c - Latent heat of c2h6 (J.kg-1) |
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| 529 | Lv =581.e3 ! eq (7-9.4) Reid et al. |
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| 530 | fte=(1.-temp/tc2h6) |
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| 531 | if (fte.le.1.e-3) fte=1.e-3 |
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| 532 | Lv=8.314*tc2h6*(7.08*fte**0.354+10.95*wc2h6*fte**0.456)/30.e-3 |
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| 533 | |
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| 534 | |
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| 535 | |
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| 536 | c - Constant to compute gas mean free path |
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| 537 | c l= (T/P)*a, with a = ( 0.707*8.31/(4*pi*molrad**2 * avogadro)) |
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| 538 | |
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| 539 | a = 0.707*rgp/(4 * pi* (moln2*1.e10)**2 * (nav*1.e-20)) |
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| 540 | |
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| 541 | c - Compute Dv, methane vapor diffusion coefficient |
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| 542 | c accounting for both kinetic and continuum regime of diffusion, |
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| 543 | c the nature of which depending on the Knudsen number. |
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| 544 | |
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| 545 | Dv = 1./3. * sqrt( 8*rgp*temp/(pi*Mc2h6) )* (kbz*1.e20) * temp / |
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| 546 | & (pi*press*(moln2*1.e10+molc2h6*1.e10)**2 * sqrt(1.+Mc2h6/Mn2) ) |
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| 547 | |
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| 548 | knudsen = temp / press * a / r |
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| 549 | lambda = (1.333+0.71/knudsen) / (1.+1./knudsen) |
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| 550 | Dv = Dv / (1. + lambda * knudsen) |
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| 551 | |
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| 552 | c - Compute Rk |
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| 553 | Rk = Lv**2 * rhoi_c2h6 * Mc2h6 / (k*rgp*temp**2.) |
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| 554 | c - Compute Rd |
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| 555 | Rd = rgp * temp *rhoi_c2h6 / (Dv*psat*Mc2h6) |
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| 556 | |
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| 557 | c - Compute: rdr/dt = Cste * (S-Seq) |
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| 558 | Cste = 1. / (seq*Rk+Rd) |
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| 559 | |
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| 560 | RETURN |
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| 561 | END |
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| 562 | |
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| 563 | |
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| 564 | ********************************************************* |
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| 565 | real function sig2(t) |
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| 566 | * this function computes the surface tension (N.m) * |
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| 567 | * between methane and air as a function of temp. * |
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| 568 | * Eq (12-3-6 et 12-3-7 Reid et al.) |
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| 569 | * |
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| 570 | ********************************************************* |
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| 571 | |
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| 572 | real t |
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| 573 | |
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| 574 | pc=48.8*1.01325e5 |
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| 575 | tc=305.4 |
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| 576 | tb=184.6 |
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| 577 | tr=t/tc |
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| 578 | tbr=tb/tc |
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| 579 | if(t.gt.305.0) then |
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| 580 | tr=305./tc |
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| 581 | endif |
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| 582 | |
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| 583 | sig2=0.1196*(1.+(tbr*alog(pc/1.01325))/(1.-tbr))-0.279 |
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| 584 | sig2=pc**(2./3.)*tc**(1./3.)*sig2*(1.-tr)**(11./9.) |
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| 585 | sig2=sig2*1.e-8 |
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| 586 | |
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| 587 | |
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| 588 | |
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| 589 | |
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| 590 | c sig2 = 21.157*((305.4-t)/(305.4-153.2))**(11./9.) |
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| 591 | c sig2=sig2*1.e-4 |
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| 592 | c |
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| 593 | c if(t.gt.305.0) then |
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| 594 | c sig2 = 21.157*((305.4-305.)/(305.4-153.2))**(11./9.) |
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| 595 | c sig2=sig2*1.e-4 |
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| 596 | c endif |
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| 597 | c |
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| 598 | c print*,t,sig2,sig3 |
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| 599 | |
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| 600 | return |
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| 601 | end |
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| 602 | |
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| 603 | ********************************************************* |
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| 604 | real*8 function fshape2(cost,rap) |
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| 605 | * function computing the f(m,x) factor * |
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| 606 | * related to energy required to form a critical embryo * |
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| 607 | ********************************************************* |
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| 608 | |
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| 609 | implicit none |
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| 610 | |
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| 611 | real cost |
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| 612 | real*8 rap |
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| 613 | real*8 phi |
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| 614 | real*8 a,b,c |
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| 615 | |
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| 616 | |
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| 617 | phi = sqrt( 1. - 2.*cost*rap + rap**2 ) |
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| 618 | a = 1. + ( (1.-cost*rap)/phi )**3 |
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| 619 | b = (rap**3) * (2.-3.*(rap-cost)/phi+((rap-cost)/phi)**3) |
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| 620 | c = 3. * cost * (rap**2) * ((rap-cost)/phi-1.) |
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| 621 | |
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| 622 | fshape2 = 0.5*(a+b+c) |
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| 623 | |
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| 624 | if (rap.gt.3000.) fshape2 = ((2.+cost)*(1.-cost)**2)/4. |
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| 625 | |
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| 626 | return |
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| 627 | end |
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| 628 | |
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