[lingdeer]

Hi, I am simulating blood flow through blood vessel and have been facing some problems that I can't reference to in the CFX manual documents.

1) The first time I used coupling convergence of 1e-2, source term of 300 (This is from trial and error until my simulation won't crash). However when I monitor two supposed-to-be symmetric points, it gives me unequal mesh displacement. Also, the solution fail to converge after running for 30 cycles (for each cycle I imposed sinusoidal velocity inflow profile. Outlet I imposed static pressure = 0Pa). Fluid convergence = RMS 1e-5
Therefore, I realize I need to tighten my coupling convergence to lower value to improve convergence.

Now, I changed to coupling convergence to 1e-3, the two monitor points now have equal values. And the mesh displacement waveform of those two points make more sense. Also, since they are at a junction, it will have the biggest displacement in the entire domain. These points are downstream of the flow, so biggest mesh displacement happen later in the cycle. However, when I run with this new coupling convergence, it crashed at the 60th timestep (each cycle time = 1s, time step = 0.01s), which is the point it reaches the biggest mesh displacement and start to retract to its original position.

Since it crash at the middle of the simulation, it's hard to check if it the source term/parameters are good at the beginning of the simulation.

I wonder for anyone who simulate blood flow in blood vessel with CFX can give me some hints on the parameters that I should use to ensure it run smoothly. e.g. what source term do you use? coefficient loop?

2) FSI simulation occupies diskspace. Until it reaches transient convergence (low cycle-to-cycle variation), I don't need results of earlier timestep, but only the last few cycles. So for fluid I know I can delete the previous .trn files to save diskspace. For solid, (.ansys folder), anyone knows how to save space? What files are necessary to keep are what are not (fluid and ansys)?

Thanks Thanks Thanks!