PATCH(HIGHWALL,HWALL,1,NX,1,NY,NZ,NZ,1,LSTEP)
IF(NX.GT.1) THEN
 COVAL(HIGHWALL,U1,1.0,0.0)
ENDIF   
IF(NY.GT.1) THEN
 COVAL(HIGHWALL,V1,1.0,0.0)
ENDIF