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This commit is contained in:
Dave Goodwin 2005-10-21 01:03:40 +00:00
parent 5f6f2481f3
commit 219649e5ac
1 changed files with 12 additions and 7 deletions
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19
Cantera/python/examples/gasdynamics/soundSpeeds.py
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@ -3,11 +3,13 @@ import math
def equilSoundSpeeds(gas):
"""Returns the equilibrium and frozen sound speeds for a gas. The
gas is first set to an equilibrium state, since otherwise the
equilibrium sound speed is not defined. Therefore, both sound
speeds are for a gas with an equilibrium composition - not the
composition of the gas object on entry."""
"""Returns a tuple containing the equilibrium and frozen sound
speeds for a gas with an equilibrium composition. The gas is
first set to an equilibrium state at the temperature and pressure
of the gas, since otherwise the equilibrium sound speed is not
defined.
"""
# set the gas to equilibrium at its current T and P
gas.equilibrate('TP')
@ -17,12 +19,12 @@ def equilSoundSpeeds(gas):
p0 = gas.pressure()
r0 = gas.density()
# perturb density
# perturb the density
r1 = r0*1.0001
# set the gas to a state with the same entropy and composition but
# the perturbed density
gas.setState_SV(s0, 1.0/r1)
gas.set(S = s0, V = 1.0/r1)
# save the pressure for this case for the frozen sound speed
pfrozen = gas.pressure()
@ -32,7 +34,10 @@ def equilSoundSpeeds(gas):
p1 = gas.pressure()
# equilibrium sound speed
aequil = math.sqrt((p1 - p0)/(r1 - r0));
# frozen sound speed
afrozen = math.sqrt((pfrozen - p0)/(r1 - r0));
return (aequil, afrozen)