Immersed boundary method with momentum forcing

Fuka

Hello, does anybody have experiences with Immersed boundary method? I'm trying version with momentum forcing(Kim,Kim,Choi 2001 like in Fadlun et al. or Mohd Yusof et al.) I have problems with computation of pressure with pressure correction (fractional step method with lagged pressure gradient) maybe because of bad initial or boundary conditions. I have simple flow around a cube. How can I treat a body in initial conditions? How can I compute initial pressure? Now I tried simple IC U=Uin and p=0 and then impose IB forcing in first step but I'm getting great pressure gradient in x direction. In Poisson equation I use dPhi/dn=0. Can anybody help?