I am now trying to use the IBM implementation by Zeljko Tukovi´c and Hrvoje Jasak. The building process was very smooth with OpenFOAM 1.6-ext. And the calculation goes on well with single processor. When I tried to utilized the parallel computation, I got error about MPI communication. The error is evoked when the Neumann boundary condition on the immersed boundary is invovled. I have tried the calculation in different computer with different operation system, but the same error appears. Can you help me to find the cause of such error?