From 9b946cb2098a104107140c75d460157afb6387b6 Mon Sep 17 00:00:00 2001
From: Grzegorz Kowal <grzegorz@gkowal.info>
Date: Mon, 8 Dec 2008 20:38:46 -0600
Subject: [PATCH] Added two subroutines to convert between variables.

Two subroutines, cons2prim and prim2cons, to convert between
conservative and primitive variables have been added.

New parameters, gammam1 and gammam1i have been added to the
configuration file. Both are derivation of gamma, first is gamma-1, the
secons 1/(gamma-1).
---
 src/config.F90 |  7 ++--
 src/scheme.F90 | 92 +++++++++++++++++++++++++++++++++++++++++++++++---
 2 files changed, 92 insertions(+), 7 deletions(-)

diff --git a/src/config.F90 b/src/config.F90
index d5e4423..520ec99 100644
--- a/src/config.F90
+++ b/src/config.F90
@@ -61,7 +61,8 @@ module config
 
 ! equation of state parameters (gamma, sound speed)
 !
-  real           , save :: gamma = 1.001, csnd = 1.0, csnd2 = 1.0
+  real           , save :: gamma = 1.001, csnd = 1.0, csnd2 = 1.0  &
+                         , gammam1 = 0.001, gammam1i = 100.0
 
   contains
 !
@@ -184,7 +185,9 @@ module config
     kgrids = ngrids
 #endif /* */
 
-    csnd2 = csnd * csnd
+    gammam1  = gamma - 1.0
+    gammam1i = 1.0 / gammam1
+    csnd2    = csnd * csnd
 
 ! return before error messages
 !
diff --git a/src/scheme.F90 b/src/scheme.F90
index 6eca87c..a2bc846 100644
--- a/src/scheme.F90
+++ b/src/scheme.F90
@@ -219,13 +219,13 @@ module scheme
 
 ! calculate primitive variables
 !
-!     call cons2prim(n,ul,ql)
-!     call cons2prim(n,ur,qr)
+    call cons2prim(m,n,ul,ql)
+    call cons2prim(m,n,ur,qr)
 #else /* CONREC */
 
 ! calculate primitive variables
 !
-!     call cons2prim(n,uc,qc)
+    call cons2prim(m,n,uc,qc)
 
 ! reconstruct left and right states of primitive variables
 !
@@ -235,8 +235,8 @@ module scheme
 
 ! calculate conservative variables at states
 !
-!     call prim2cons(n,ql,ul)
-!     call prim2cons(n,qr,ur)
+    call prim2cons(m,n,ql,ul)
+    call prim2cons(m,n,qr,ur)
 #endif /* CONREC */
 
 ! calculate fluxes and speeds
@@ -335,6 +335,88 @@ module scheme
 !----------------------------------------------------------------------
 !
   end subroutine fluxspeed
+!
+!===============================================================================
+!
+! cons2prim: subroutine to calculate primitive variables from conservative ones
+!
+!===============================================================================
+!
+  subroutine cons2prim(m, n, u, q)
+
+    use config   , only : gammam1
+
+    implicit none
+
+! input/output arguments
+!
+    integer             , intent(in)  :: m, n
+    real, dimension(m,n), intent(in)  :: u
+    real, dimension(m,n), intent(out) :: q
+
+! local variables
+!
+    integer :: i
+    real    :: dni
+!
+!----------------------------------------------------------------------
+!
+    do i = 1, n
+      dni    = 1.0 / u(1,i)
+
+      q(1,i) =     u(1,i)
+      q(2,i) = dni*u(2,i)
+      q(3,i) = dni*u(3,i)
+      q(4,i) = dni*u(4,i)
+#ifdef ADI
+      q(5,i) = u(5,i) &
+             - 0.5*(u(2,i)*q(2,i) + u(3,i)*q(3,i) + u(4,i)*q(4,i))
+      q(5,i) = gammam1*q(5,i)
+#endif /* ADI */
+    enddo
+
+!----------------------------------------------------------------------
+!
+  end subroutine cons2prim
+!
+!===============================================================================
+!
+! prim2cons: subroutine to calculate conservative variables from primitive ones
+!
+!===============================================================================
+!
+  subroutine prim2cons(m, n, q, u)
+
+    use config, only : gammam1i
+
+    implicit none
+
+! input/output arguments
+!
+    integer             , intent(in)  :: m, n
+    real, dimension(m,n), intent(in)  :: q
+    real, dimension(m,n), intent(out) :: u
+
+! local variables
+!
+    integer :: i
+!
+!----------------------------------------------------------------------
+!
+    do i = 1, n
+      u(1,i) = q(1,i)
+      u(2,i) = q(1,i)*q(2,i)
+      u(3,i) = q(1,i)*q(3,i)
+      u(4,i) = q(1,i)*q(4,i)
+#ifdef ADI
+      u(5,i) = gammam1i*q(5,i) &
+             + 0.5*(u(2,i)*q(2,i) + u(3,i)*q(3,i) + u(4,i)*q(4,i))
+#endif /* ADI */
+    enddo
+
+!----------------------------------------------------------------------
+!
+  end subroutine prim2cons
 
 !======================================================================
 !