anchor.diff:      end do
     end subroutine
     
  -  !> predict the momentum with current pressure
  +  !> predict the rhou1 and flowRho without acceleration by pressure
     subroutine predictMomentum()
       use modGradient
       use modPressure
  
positive.code:       allocate(tmpP(grid%nC))
      end if
      tmpP(:)=p(1:grid%nC)
      call setBC()
      call findViscForce(grid,u,visc,viscF)
      forall(i=1:grid%nE,j=1:DIMS)
        fluxRhou(:,j,i)=rhou(j,i)*u(:,i)
      end forall
      call findAdv(grid,rhou,fluxRhou,flowRhou)
      forall(i=1:grid%nC)
        rhou1(:,i)=rhou0(:,i)+dt/grid%v(i)*(flowRhou(:,i)+viscF(:,i)) ! pressure force excluded
      end forall
      call pressureEq%solve(tmpP,info=info)
      needRetry=info<0
      call pressureEq%getNIt(n)
  
negative.code:       deallocate(tmpRhou)
        allocate(tmpRhou(DIMS*grid%nC))
      end if
      ! solve momentum equation with current pressure
      tmpRhou=reshape(rhou(:,1:grid%nC),[DIMS*grid%nC])
      call setBC()
      call findGrad(grid,p,gradP)
  