Projection method and Block-off method

Leo

Hi,there,

when using Projection method to simulate the incompressible flow around bodies,I choose the Block-off method(Patankar) which is easy to deal with the boundary conditions for flow around bodies,while,FVM is used,the velocities of the bodies are prescribed and the momentum equ.are solved for temperal velocities(among bodies,large enough source terms are used to get the velocities prescribed among the bodies),then,possion equ.for pressure is solved to get the pressure values among the domain including those among bodies,at the 3nd step,I use the pressure values to correct the temperal velocity field,for the convergence at this time step,i use the cell's maxium residual of the continuity,the trouble apperars:1.if at the 3nd step,donot use the pressure values to correct the prescribled velocities among the bodies,then,as the iteration num. increased,the cell's maxium residual of continuity stays at large value and donot decrease,2.if at the 3nd step,use the pressure values to correct the prescribled velocities among the bodies,finally,at the end of this time step,the velocities on the bodied will change and donot equal to the prescribed values.

I have been mixed on this problem for a long time,anyone have this experence,please help.

thanks in advance

Leo