Keyur Kanade
Ansys Employee
Duplicate of n

Hi all,For my PhD project, I'm working on fluid-structure interaction (FSI) models of abdominal aortic aneurysms (AAA) using Ansys Mechanical APDL, Fluent and System Coupling (version 2020R1). I've been able to simulate quite a few FSI models, but I'm facing problems with a subset of models. The flow and pressure at the inlet and outlet of the model are written to a text file. If I plot the flow for a successful model, I get something that looks like this:Flow - successful model the pressure (outlet pressure calculated using a 3-element Windkessel model) looks like this:Pressure - successful model, If I plot the flow and pressure for a unsuccessful model, I get:Flow - unsuccessful model time = 1.735 s, a high increase in outlet flow can be seen.Pressure - unsuccessful model in at the pressure around t = 1.735 s, a sharp increase in inlet pressure can be seen. The outlet pressure (prescribed using the Windkessel model) doesn't show any abnormalities in this step. Therefore, I think the prescribed pressure at the outlet at t = 1.735 s is correct. However, I don't understand why the outlet flow is suddenly increased in this timestep. Due to this sudden flow increase, the pressure is altered as well, causing a weird pressure profile. In this model, the simulation still finished, but in two other models, a similar sudden jump in flow is observed and the simulation crashes later on (after 0.5 or even 1.5 cycles). If I look at the velocity vectors, streamlines, pressure, WSS and displacements of the last cardiac cycle (starting at 1.6 s), I don't see any abnormalities until the sudden jump in flow. I've included the videos of the velocity vectors and streamlines. know it's a long shot, but I was hoping one of you could help me find the problem (and hopefully, I can find a solution). Is there anyone who can point me towards the correct direction?Thanks in advance!Best regards,Judith