Don't extrapolate momenta at zhi if dirichlet (#2695)

Author: ewquon

Source/Utils/ERF_VelocityToMomentum.cpp

@@ -197,12 +197,17 @@ void VelocityToMomentum (const MultiFab& xvel_in,
         // Extrapolate momenta at top of domain (in case they need to be used in OmegaFromW)
         if (bx.bigEnd(2) == domain.bigEnd(2))
         {
-            ParallelFor(makeSlab(tbx,2,domain.bigEnd(2)+1), [=] AMREX_GPU_DEVICE (int i, int j, int k) {
-                momx(i,j,k) = momx(i,j,k-1);
-            });
-            ParallelFor(makeSlab(tby,2,domain.bigEnd(2)+1), [=] AMREX_GPU_DEVICE (int i, int j, int k) {
-                momy(i,j,k) = momy(i,j,k-1);
-            });
+            if (bc_ptr_h[BCVars::xvel_bc].hi(2) != ERFBCType::ext_dir) {
+                ParallelFor(makeSlab(tbx,2,domain.bigEnd(2)+1), [=] AMREX_GPU_DEVICE (int i, int j, int k) {
+                    momx(i,j,k) = momx(i,j,k-1);
+                });
+            }
+
+            if (bc_ptr_h[BCVars::yvel_bc].hi(2) != ERFBCType::ext_dir) {
+                ParallelFor(makeSlab(tby,2,domain.bigEnd(2)+1), [=] AMREX_GPU_DEVICE (int i, int j, int k) {
+                    momy(i,j,k) = momy(i,j,k-1);
+                });
+            }
         }
     } // end MFIter
 }