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Last change
on this file since 1242 was
943,
checked in by aslmd, 12 years ago
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clean and organized UTIL/PYTHON folder
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-
Property svn:executable set to
*
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File size:
997 bytes
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| 1 | #! /usr/bin/env python |
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| 2 | |
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| 3 | import sys |
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| 4 | |
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| 5 | T = float(sys.argv[1]) |
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| 6 | P = float(sys.argv[2]) |
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| 7 | |
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| 8 | ### For dust |
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| 9 | radius = 2.e-6 ## m |
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| 10 | rho = 2500. ## kg / m3 |
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| 11 | |
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| 12 | ### For Mars |
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| 13 | R = 192. ## m2/s2/K |
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| 14 | rhoair = P / R / T |
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| 15 | grav = 3.72 ## m / s2 |
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| 16 | visc = 1.e-5 ## Gas molecular viscosity (N s / m2) |
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| 17 | molrad = 2.2e-10 ## Effective gas molecular radius (m) |
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| 18 | |
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| 19 | ## Constant to compute stokes speed simple formulae |
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| 20 | ## Vstokes = b * rho * r**2 avec b = (2/9) * rho * g / visc |
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| 21 | b = (2./9.) * grav / visc |
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| 22 | |
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| 23 | ## Constant to compute gas mean free path |
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| 24 | ## l= (T/P)*a, avec a = ( 0.707*8.31/(4*pi*molrad**2 * avogadro)) |
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| 25 | a = 0.707 * 8.31 / ( 4 * 3.1416 * molrad * molrad * 6.023e23 ) |
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| 26 | |
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| 27 | ## Sedimentation velocity (m/s) |
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| 28 | ## (stokes law corrected for low pressure by the Cunningham |
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| 29 | ## slip-flow correction according to Rossow (Icarus 36, 1-50, 1978) |
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| 30 | vstokes = b * rho * radius * radius * (1 + 1.333* ( a / 192. / rhoair ) / radius) |
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| 31 | |
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| 32 | print "--- for T = %.0f K and P = %.0f Pa" % (T,P) |
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| 33 | print "rho = %4.2e kg/m3 and vsedim = %4.2e m/s" % (rhoair,vstokes) |
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