Changeset 120 for codes

Timestamp:

02/01/13 00:12:53 (11 years ago)

Author:

dubos

Message:

RK4 time stepping scheme

File:

• codes/icosagcm/trunk/src/timeloop_gcm.f90 (modified) (3 diffs)

codes/icosagcm/trunk/src/timeloop_gcm.f90

@@ -124 +124 @@
         CALL leapfrog_scheme
 
+      CASE ('runge_kutta')
+        CALL rk_scheme
+
       CASE ('leapfrog_matsuno')
         CALL  leapfrog_matsuno_scheme
@@ -133 +136 @@
       CASE default
         PRINT*,'Bad selector for variable scheme : <', TRIM(scheme),             &
-               ' > options are <euler>, <leapfrog>, <leapfrog_matsuno>, <adam_bashforth>'
+               ' > options are <euler>, <runge_kutta>, <leapfrog>, <leapfrog_matsuno>, <adam_bashforth>'
         STOP
         
@@ -157 +160 @@
       
     END SUBROUTINE Euler_scheme
-    
+
+    SUBROUTINE RK_scheme
+      IMPLICIT NONE
+      INTEGER :: ind, stage
+      REAL(rstd), DIMENSION(4), PARAMETER :: coef = (/ 1., 4./3., 2., 4. /)
+      REAL(rstd) :: tau
+
+      stage = MOD(it,4)+1
+      tau = dt*coef(stage)
+
+      DO ind=1,ndomain
+         ps=f_ps(ind)   ; u=f_u(ind)   ; theta_rhodz=f_theta_rhodz(ind)
+         psm1=f_psm1(ind) ; um1=f_um1(ind) ; theta_rhodzm1=f_theta_rhodzm1(ind)
+         dps=f_dps(ind) ; du=f_du(ind) ; dtheta_rhodz=f_dtheta_rhodz(ind)
+
+         IF (stage==1) THEN
+            psm1(:)=ps(:) ; um1(:,:)=u(:,:) ; theta_rhodzm1(:,:)=theta_rhodz(:,:)
+         END IF
+         ps(:)=psm1(:)+tau*dps(:)
+         u(:,:)=um1(:,:)+tau*du(:,:)
+         theta_rhodz(:,:)=theta_rhodzm1(:,:)+tau*dtheta_rhodz(:,:)
+      END DO
+    END SUBROUTINE RK_scheme
+
     SUBROUTINE leapfrog_scheme
     IMPLICIT NONE