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EQUATIONS: Fix and optimize SRHD 2D(W,u²) primitive variable solver.

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One of the derivative was calculated in a wrong way. This patch also
incorporates the pressure derivatives directly in the derivatives of
functions F(W,u²) and G(W,u²), which allows to some microoptimizations.

Signed-off-by: Grzegorz Kowal <grzegorz@amuncode.org>
This commit is contained in:
Grzegorz Kowal 2015-02-19 17:17:38 -02:00
parent 28badcb066
commit a470a2a874
1 changed files with 6 additions and 12 deletions
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18
src/equations.F90
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@ -3817,7 +3817,7 @@ module equations
!
logical :: keep
integer :: it, cn
real(kind=8) :: ww, uu, up, gm, tm
real(kind=8) :: ww, uu, up, gm
real(kind=8) :: pr, dpw, dpu
real(kind=8) :: f, dfw, dfu, df
real(kind=8) :: g, dgw, dgu, dg
@ -3857,27 +3857,21 @@ module equations
up = 1.0d+00 + uu
gm = sqrt(up)
! calculate the thermal pressure and its derivatives
! calculate the thermal pressure
!
! P(W,|V|²) = (γ - 1)/γ (W - D Γ) / (1 + |u|²)
! dP/dW = (γ - 1)/γ / (1 + |u|²)
! dP/d|V|² = (γ - 1)/γ (½ D Γ - W) / (1 + |u|²)²
!
tm = dn * gm
pr = gammaxi * (w - tm) / up
dpw = gammaxi / up
dpu = gammaxi * (0.5d+00 * tm - w) / up**2
dw = w - en - pr
pr = gammaxi * (w / up - dn / gm)
! calculate F(W,|V|²) and G(W,|V|²)
!
f = dw * up
f = (w - en - pr) * up
g = ww * uu - mm * up
! calculate dF(W,|V|²)/dW and dF(W,|V|²)/d|V|²
!
dfw = up * (1.0d+00 - dpw)
dfu = dw - dpu
dfw = up - gammaxi
dfu = w - en + 0.5d+00 * gammaxi * dn / gm
! calculate dG(W,|V|²)/dW and dG(W,|V|²)/d|V|²
!