Annoying FSI error

taedeneo

Hi all, I am doing a simple FSI simulation of a pipe flow. I have been trying to do a 2D FSI simulation in ANSYS(CFX+ANSYS). I have the error messages below

################################################## #### (1) ERROR #002100061 has occurred in subroutine SERVE_CLIENTS Message: The connection between this CFX process and an external process has died unexpectedly. The following error was_received: External_process :ANSYS Error experienced : Read ** This error is fatal: Terminating ANSYS CFX Solver execution ** Please review the output, error and log files from both the CFX and external processes to determine the cause of the error. (2)this is in the .err file. "One or more elements have become highly distorted. Excessive distortion of elements is usually a symptom indicating the need for_corrective action elsewhere. Try ramping the load up instead of step_applying the load (KBC,1). You may need to improve your mesh to obtain elements with better aspect ratios. Also consider the behavior of materials, contact pairs, and/or constraint_equations.If this message appears in the first iteration of first substep,be_sure_to_run_shape_checking_of_elements. " ################################################## ######## ################################################## #########

I tried to run the fluid part separately(stationary case) with the same setup and the result came out as normal and look very physical after checking velocity and pressure. So I assumed that there is nothing wrong with the fluid part.

Another thing that i don't understand is that based on the error message, it is suggested that the solver failed because of the mesh distortion while the inlet velocity is only 0.015. Also it is straight pipe so the only excitation will be only due to turbulence fluctuation which shouldn't give huge pipe's deformation and thus mesh distortion.

I would be appreciate it if somebody could help

all the best Taedeneo

It is also interesting that I have successfully done this flow problem with the same setup but a coarse 3D mesh.

I am wondering if this has something to do