diff --git a/code/ysolve.f90 b/code/ysolve.f90
index fed339a..5a14813 100644
--- a/code/ysolve.f90
+++ b/code/ysolve.f90
@@ -101,7 +101,8 @@
 
      SUBROUTINE solve_with_diffusivity (calc_diff)
       INTERFACE
-       SUBROUTINE calc_diff
+       SUBROUTINE calc_diff(r1)
+        REAL, INTENT(IN),  DIMENSION(:,:) :: r1
        END SUBROUTINE calc_diff
       END INTERFACE
 
@@ -126,7 +127,8 @@
        SUBROUTINE SET_IC
        END SUBROUTINE SET_IC
 
-       SUBROUTINE calc_diff
+       SUBROUTINE calc_diff(r1)
+        REAL, INTENT(IN),  DIMENSION(:,:) :: r1
        END SUBROUTINE calc_diff
       END INTERFACE
 
@@ -163,7 +165,7 @@
 
        CALL SET_BC
 
-       CALL RK4(rhs)
+       CALL RK4(rhs, calc_diff)
 
        IF (t_uf.ge.dt_uf) THEN
          pflold=pflame
@@ -478,13 +480,17 @@
 
      END SUBROUTINE finalize_solver
 
-     SUBROUTINE RK4(rhs)
+     SUBROUTINE RK4(rhs, calc_diff)
 
       INTERFACE
        SUBROUTINE rhs(r1,f)
         REAL, INTENT(IN),  DIMENSION(:,:) :: r1
         REAL, INTENT(OUT), DIMENSION(:,:) :: f
        END SUBROUTINE rhs
+
+       SUBROUTINE calc_diff(r1)
+        REAL, INTENT(IN),  DIMENSION(:,:) :: r1
+       END SUBROUTINE calc_diff
       END INTERFACE
 
        CALL substep(1,y1,y1,y2,yf)
@@ -516,7 +522,7 @@
       INTEGER :: i,j,k
       REAL :: at,bt
 
-       CALL update_dm
+       CALL calc_diff(ri)
 
        CALL rhs(ri,f)
 
@@ -533,7 +539,8 @@
 
      END SUBROUTINE RK4
 
-     SUBROUTINE update_dm
+     SUBROUTINE update_dm(r1)
+      REAL, INTENT(IN),DIMENSION(:,:) :: r1
       INTEGER :: i
 
       DO i=1,nx
@@ -541,6 +548,15 @@
       ENDDO
      END SUBROUTINE update_dm
 
+     SUBROUTINE update_dm_cd(r1)
+      REAL, INTENT(IN),DIMENSION(:,:) :: r1
+      INTEGER :: i
+
+      DO i=1,nx
+        dm(i) = diff + d_turb
+      ENDDO
+     END SUBROUTINE update_dm_cd
+
      SUBROUTINE fonestep(r1,f)
       REAL, INTENT(IN),DIMENSION(:,:) :: r1
       REAL, INTENT(OUT),DIMENSION(:,:) :: f