stiffgas.F

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!||====================================================================
!||    stiffgas   ../common_source/eos/stiffgas.F
!||--- called by ------------------------------------------------------
!||    eosmain    ../common_source/eos/eosmain.F
!||====================================================================
      SUBROUTINE stiffgas
     1                    (iflag,nel, pm    ,off  ,eint ,mu   ,mu2 ,
     2                     espe ,dvol ,df   ,vnew ,mat  ,psh ,
     3                     pnew ,dpdm ,dpde )
C-----------------------------------------------
C   M o d u l e s
C-----------------------------------------------
C
C-----------------------------------------------
C   D e s c r i p t i o n
C-----------------------------------------------
C This subroutine contains numerical solving
C of STIFFENED-GAS EOS
!----------------------------------------------------------------------------
!! \details STAGGERED SCHEME IS EXECUTED IN TWO PASSES IN EOSMAIN : IFLG=0 THEN IFLG=1
!! \details COLLOCATED SCHEME IS DOING A SINGLE PASS : IFLG=2
!! \details
!! \details  STAGGERED SCHEME
!! \details     EOSMAIN / IFLG = 0 : DERIVATIVE CALCULATION FOR SOUND SPEED ESTIMATION c[n+1] REQUIRED FOR PSEUDO-VISCOSITY (DPDE:partial derivative, DPDM:total derivative)
!! \details     MQVISCB            : PSEUDO-VISCOSITY Q[n+1]
!! \details     MEINT              : INTERNAL ENERGY INTEGRATION FOR E[n+1] : FIRST PART USING P[n], Q[n], and Q[n+1] CONTRIBUTIONS
!! \details     EOSMAIN / IFLG = 1 : UPDATE P[n+1], T[N+1]
!! \details                          INTERNAL ENERGY INTEGRATION FOR E[n+1] : LAST PART USING P[n+1] CONTRIBUTION
!! \details                            (second order integration dE = -P.dV where P = 0.5(P[n+1] + P[n]) )
!! \details  COLLOCATED SCHEME
!! \details     EOSMAIN / IFLG = 2 : SINGLE PASS FOR P[n+1] AND DERIVATIVES
!----------------------------------------------------------------------------
C-----------------------------------------------
C   I m p l i c i t   T y p e s
C-----------------------------------------------
#include      "implicit_f.inc"
#include      "comlock.inc"
C-----------------------------------------------
C   C o m m o n   B l o c k s
C-----------------------------------------------
#include      "param_c.inc"
#include      "com04_c.inc"
#include      "com06_c.inc"
#include      "com08_c.inc"
#include      "vect01_c.inc"
#include      "scr06_c.inc"
C-----------------------------------------------
C   D u m m y   A r g u m e n t s
C-----------------------------------------------
        INTEGER MAT(NEL), IFLAG, NEL
        my_real pm(npropm,nummat),
     .          off(nel)  ,eint(nel) ,mu(nel)   ,
     .          mu2(nel)  ,espe(nel) ,dvol(nel) ,df(nel)  ,
     .          vnew(nel) ,pnew(nel) ,dpdm(nel),
     .          dpde(nel)
        my_real, INTENT(INOUT) :: psh(nel)
C-----------------------------------------------
C   L o c a l   V a r i a b l e s
C-----------------------------------------------
        INTEGER I, MX
        my_real :: p0,gamma,t0,e0,sph,aa, bb, dvv, pp, pstar, pc
C-----------------------------------------------
C   S o u r c e  L i n e s
C-----------------------------------------------
        IF(iflag == 0) THEN
          mx         = mat(1)
          e0         = pm(23,mx)
          gamma      = pm(34,mx)
          p0         = pm(32,mx)
          psh(1:nel) = pm(88,mx)
          pstar      = pm(35,mx)
          sph        = pm(69,mx)
          pc         = pm(37,mx)
          DO i=1,nel
            pp      = -gamma*pstar-psh(i) + (gamma-one)*(one+mu(i))*espe(i)
            dpdm(i) =  (gamma-one) *espe(i)+(gamma-one)*(one+mu(i))*df(i)*df(i)*(pp+psh(i) )
            dpde(i) = (gamma-one)*(one+mu(i))
            pnew(i) = max(pp,pc-psh(i))*off(i) ! P(mu[n+1],E[n])
          ENDDO
 
        ELSEIF(iflag == 1) THEN
          mx         = mat(1)
          e0         = pm(23,mx)
          gamma      = pm(34,mx)
          p0         = pm(32,mx)
          psh(1:nel) = pm(88,mx)
          pstar      = pm(35,mx)
          sph        = pm(69,mx)
          pc         = pm(37,mx)
          DO i=1,nel
            aa      = -gamma*pstar-psh(i)
            bb      = (gamma-one)*(one+mu(i))
            dpde(i) = (gamma-one)*(one+mu(i))
            dvv     = half*dvol(i)*df(i) / max(em15,vnew(i))
            pnew(i) = (aa+bb*(espe(i)-psh(i) *dvv))/(one+bb*dvv)
            pnew(i) = max(pnew(i),pc-psh(i) )*off(i)  ! P(mu[n+1],E[n+1])
            eint(i) = eint(i) - half*dvol(i)*(pnew(i)+psh(i) )
          ENDDO
 
        ELSEIF(iflag == 2) THEN
          mx           = mat(1)
          e0           = pm(23,mx)
          gamma        = pm(34,mx)
          p0           = pm(32,mx)
          psh(1:nel) = pm(88,mx)
          pstar        = pm(35,mx)
          sph          = pm(69,mx)
          pc = pm(37, mx)
          DO i=1, nel
            IF (vnew(i) > zero) THEN
              pnew(i) = (gamma-one)*(one+mu(i))*espe(i) - gamma*pstar
              pnew(i) = max(pnew(i),pc)*off(i)
              !EINT(I) = (PNEW(I) + PSH(I) + GAMMA * PSTAR) / (GAMMA - ONE)
              dpdm(i) = (gamma-one)*(espe(i)+pnew(i)*df(i)) !total derivative
              dpde(i) = (gamma-one)*(one+mu(i)) !partial derivative
              pnew(i) = pnew(i)-psh(i)
            ENDIF
          ENDDO
        ENDIF
C-----------------------------------------------
        RETURN
      END