Hello,
I want to reproduce the experimental results of a FDA-study (https://fdacfd.nci.nih.gov/interlab_study_1_nozzle/documentation/) with AcuSolve. The experimental assembly consists of a narowing of the cross-section und afterwards a sudden expansion of a channel. The tests run with different flow conditions (Re = 500 till Re = 6500 in the narrowing). If the Re is greater or equal 2000, it is getting intresting. To gain experience with AcuSolve I want to simulate the “easy” laminar flow (Re = 500). But there are aleady problems.
I generate 3 meshes with HyperMesh. The first one with about 150000 elements. In the narrowing the axial velocity along the centerline (z-axis) oscillates. After changing the simulation conditions, like the number of time steps, the time increment, the convergence tolerance, the relaxation factor and so on, without an effect on the results. Becuase of that I generate a second mesh with about 300000 elements. The axial velocity along the centerline does not oszillate any more, but it is to low. With a mesh consists of about 900000 elements the axial velocity drops again.
My supervisor, Mike Nicolai, and I have no more ideas. Can someone help me?


