matrix coefficients

dominik

Hallo, I need advise on the following issue. I linearised my NS equations (finite diff. uniform cart.grid) as A_0*phi_0 + sum_nb (A_nb*phi_nb) = Source, with \phi = u,v,pres_corr., source = gradp,mass_term. I solve first mom.eq and then pres.corr equation (SIMPLE) that way. I get the right driven cavity, tube etc. but the question is what do I do with those coefficients BOTH in momentum AND in pcor. equation close to immersed boundaries? I get jiggles close to cylinder... In momentum eq. I put A_nb = 0 close to boundary and increase A_0 accordingly, in p.cor I keep all A_nb's and use pp_nb=pp_0 close to wall (zero normal gradient). Why do I get jiggles close to objects? Thanks a lot Dominik