import numpy as np
from numba import njit
[docs]
@njit(cache=True)
def f(p, U_ij, gamma, idens, ixmom, iymom, iener):
"""
Function whose root needs to be found for cons to prim
"""
D = U_ij[idens]
tau = U_ij[iener]
if abs(tau+p) < 1.e-6:
u = U_ij[ixmom]
v = U_ij[iymom]
else:
u = U_ij[ixmom] / (tau + p + D)
v = U_ij[iymom] / (tau + p + D)
# Lorentz factor
W = 1.0 / np.sqrt(1.0 - u**2 - v**2)
return (gamma - 1.0) * (tau + D*(1.0-W) + p*(1.0-W**2)) / W**2 - p
[docs]
@njit(cache=True)
def brentq(x1, b, U, gamma, idens, ixmom, iymom, iener,
TOL=1.e-6, ITMAX=100):
"""
Root finder using Brent's method
"""
# initialize variables
a = x1
c = 0.0
d = 0.0
fa = f(a, U, gamma, idens, ixmom, iymom, iener)
fb = f(b, U, gamma, idens, ixmom, iymom, iener)
fc = 0.0
# root found
if fa * fb >= 0.0:
return x1
# switch variables
if abs(fa) < abs(fb):
a, b = b, a
fa, fb = fb, fa
c = a
fc = fa
mflag = True
for _ in range(ITMAX):
if fa != fc and fb != fc: # pylint: disable=consider-using-in
s = a*fb*fc / ((fa-fb) * (fa-fc)) + b*fa*fc / ((fb-fa)*(fb-fc)) + \
c*fa*fb / ((fc-fa)*(fc-fb))
else:
s = b - fb * (b-a) / (fb-fa)
# test conditions and store in con1-con5
con1 = False
if 0.25 * (3.0 * a + b) < b:
if s < 0.25 * (3.0 * a + b) or s > b:
con1 = True
elif s < b or s > 0.25 * (3.0 * a + b):
con1 = True
con2 = mflag and abs(s-b) >= 0.5 * abs(b-c)
con3 = (not mflag) and abs(s-b) >= 0.5 * abs(c-d)
con4 = mflag and abs(b-c) < TOL
con5 = (not mflag) and abs(c-d) < TOL
if con1 or con2 or con3 or con4 or con5:
s = 0.5 * (a + b)
mflag = True
else:
mflag = False
# evaluate at midpoint and set new limits
fs = f(s, U, gamma, idens, ixmom, iymom, iener)
if abs(fa) < abs(fb):
a, b = b, a
fa, fb = fb, fa
d = c
c = b
fc = fb
if fa * fs < 0.0:
b = s
fb = fs
else:
a = s
fa = fs
# found solution to required tolerance
if fb == 0.0 or fs == 0.0 or abs(b-a) < TOL:
return b
return x1
[docs]
@njit(cache=True)
def cons_to_prim(U,
irho, iu, iv, ip, ix, irhox,
idens, ixmom, iymom, iener,
naux, gamma, q, smallp=1.e-6):
"""
convert an input vector of conserved variables to primitive variables
"""
qx, qy, _ = U.shape
for j in range(qy):
for i in range(qx):
pmax = max((gamma-1.0)*U[i, j, iener]*1.0000000001, smallp)
pmin = max(min(1.0e-6*pmax, smallp), np.sqrt(U[i, j, ixmom] **
2+U[i, j, iymom]**2) - U[i, j, iener] - U[i, j, idens])
fmin = f(pmin, U[i, j, :], gamma, idens, ixmom, iymom, iener)
fmax = f(pmax, U[i, j, :], gamma, idens, ixmom, iymom, iener)
if fmin * fmax > 0.0:
pmin = pmin * 1.0e-2
fmin = f(pmin, U[i, j, :], gamma, idens, ixmom, iymom, iener)
if fmin * fmax > 0.0:
pmax = min(pmax*1.0e2, 1.0)
if fmin * fmax > 0.0:
q[i, j, ip] = max((gamma-1.0)*U[i, j, iener], smallp)
else:
q[i, j, ip] = brentq(pmin, pmax, U[i, j, :], gamma, idens, ixmom, iymom, iener)
if (q[i, j, ip] != q[i, j, ip]) or \
(q[i, j, ip]-1.0 == q[i, j, ip]) or \
(abs(q[i, j, ip]) > 1.0e10): # nan or infty alert
q[i, j, ip] = max((gamma-1.0)*U[i, j, iener], smallp)
q[i, j, ip] = max(q[i, j, ip], smallp)
if abs(U[i, j, iener] + U[i, j, idens] + q[i, j, ip]) < 1.0e-5:
q[i, j, iu] = U[i, j, ixmom]
q[i, j, iv] = U[i, j, iymom]
else:
q[i, j, iu] = U[i, j, ixmom]/(U[i, j, iener] + U[i, j, idens] + q[i, j, ip])
q[i, j, iv] = U[i, j, iymom]/(U[i, j, iener] + U[i, j, idens] + q[i, j, ip])
# nan check
if (q[i, j, iu] != q[i, j, iu]):
q[i, j, iu] = 0.0
if (q[i, j, iv] != q[i, j, iv]):
q[i, j, iv] = 0.0
W = 1.0/np.sqrt(1.0 - q[:, :, iu]**2 - q[:, :, iv]**2)
q[:, :, irho] = U[:, :, idens] / W
if naux > 0:
for i in range(naux):
q[:, :, ix+i] = U[:, :, irhox+i]/(q[:, :, irho] * W)
