doubt: immersed boundary method

I have problem with implementation of IBM in the LBM. Considering the laminar flow past a 2D circular cylinder. Compared with the reference value,the drag coefficient Cd I calculated was much larger while lift coefficientwhich Cl was much lower. The LBM and Guo force model was validated by lid driven cavity flow and Poiseuille flow driven by gravity. The algorithm of multi-direct-forcing IB-LBM in “Immersed boundary methods in the lattice Boltzmann equation for flow simulation(Kang, S. K. (2010)” was adopted. Other IBM algorithms( Dupuis, Feng ) were also tested, the result were all similar.I don’t know where the bug is .

LBM: Left boundary u=(umax,0); Right boundary u(Nx,Ny)=u(Nx-1,Ny-1);Top and bottom boundary: free-slip or periodic.

Any help is appreciated,

I am working on IB-LBM with the IBM algorithms( Dupuis, Feng ) too. and have the same problems: CD and CL is too large. But when RE=40 the flow is steady and becomes unsteady at RE=100, these results are right qualitatively.

Wish other people’s reply could be helpful.

Hi tsfed
send me the algorithm so that I can help you.