Changeset 877 for palm/trunk/SOURCE/poisfft.f90

Timestamp:

Apr 3, 2012 11:21:44 AM (12 years ago)

Author:

suehring

Message:

Avoid divisions by zero in case of using a 'neumann' bc for the pressure at the top of the model domain.

File:

• palm/trunk/SOURCE/poisfft.f90 (modified) (2 diffs)

palm/trunk/SOURCE/poisfft.f90

@@ -4 +4 @@
 ! Current revisions:
 ! -----------------
-!
+! Bugfix: Avoid divisions by zero in case of using a 'neumann' bc for the
+! pressure at the top of the model domain.
 !
 ! Former revisions:
@@ -479 +480 @@
 
 !
-!--       Backward substitution.
+!--       Backward substitution
+!--       Note, the 1.0E-20 in the denominator is due to avoid divisions
+!--       by zero appearing if the pressure bc is set to neumann at the top of
+!--       the model domain.
           DO  i = nxl_z, nxr_z
 #if defined( __parallel )
-             ar(i,j,nz) = ar1(i,nz-1) / tri(4,i,nz-1)
-#else
-             ar(nz,j,i) = ar1(i,nz-1) / tri(4,i,nz-1)
+             ar(i,j,nz) = ar1(i,nz-1) / ( tri(4,i,nz-1) + 1.0E-20 )
+#else
+             ar(nz,j,i) = ar1(i,nz-1) / ( tri(4,i,nz-1) + 1.0E-20 )
 #endif
           ENDDO