import numpy as np
import compressible.eos as eos
[docs]def derive_primitives(myd, varnames):
"""
derive desired primitive variables from conserved state
"""
# get the variables we need
dens = myd.get_var("density")
xmom = myd.get_var("x-momentum")
ymom = myd.get_var("y-momentum")
ener = myd.get_var("energy")
derived_vars = []
u = xmom/dens
v = ymom/dens
e = (ener - 0.5*dens*(u*u + v*v))/dens
gamma = myd.get_aux("gamma")
p = eos.pres(gamma, dens, e)
if isinstance(varnames, str):
wanted = [varnames]
else:
wanted = list(varnames)
for var in wanted:
if var == "velocity":
derived_vars.append(u)
derived_vars.append(v)
elif var in ["e", "eint"]:
derived_vars.append(e)
elif var in ["p", "pressure"]:
derived_vars.append(p)
elif var == "primitive":
derived_vars.append(dens)
derived_vars.append(u)
derived_vars.append(v)
derived_vars.append(p)
elif var == "soundspeed":
derived_vars.append(np.sqrt(gamma*p/dens))
if len(derived_vars) > 1:
return derived_vars
else:
return derived_vars[0]