CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS

2-way FSI of artery, Divergence issues in Ansys 19.1

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   October 2, 2020, 06:36
Default 2-way FSI of artery, Divergence issues in Ansys 19.1
  #1
New Member
 
Rene Hiemstra
Join Date: Mar 2017
Posts: 7
Rep Power: 7
Frisii is on a distinguished road
Dear All,


I'm working on performing an 2-way FSI simulation on a human thoracic artery. However I'm having trouble stabilizing the initial steps of the simulation, I've tried many things to try and enhance the stabilization, but to no avail.


The FSI simulation consists of a realistic human thoracic artery through with an inlet flow-rate UDF with a plug-flow profile. The walls have an isotropic linear elastic response and the coupling is between the force data from the fluid simulation and the displacement data from the mechanical simulation.



In the attached images, File1,File2, it can be seen that distortion occurs, but only in certain areas, File1 shows how to distorted geometry looks, and File2 is an overview of all extra edges generated by the re-meshing. The divergence starts at pretty much the first time step, but it takes a while before the simulation finally crashes.


I've done both simulations separately with estimated boundary conditions and they both converged fine. I've used results from the flow simulation to initialize the flow field for the FSI simulation as well. I'm assuming the meshing is not the issue here, bot meshes are reasonably fine, with the mechanical shell being around 4/5 elements thick and the fluid having a boundary layer almost double that resolution. Meshes are tetra-dominated. My assumption that this is not the issue rests on the fact that the distortion if not evenly spread, and mostly concentrated in the flow-caps, which have the highest mesh quality due to their perfect geometry, in contrast to the rest of the artery.

My guess is that the problem lies somewhere with the Fluent dynamic re-meshing, as both sub simulations converged fine, maybe something with the meshing being to slow or too fast for the flow/displacement. Sadly I've reached the limits of my knowledge on the subject of re-meshing. I've included my current settings, and the journal file I use to submit this to the cluster.



Can someone help me figure out what is going wrong here? Do I need to adjust my re-meshing settings, or is there something else I'm overlooking? I've already set the time step to very small sizes, and I am currently trying to increase the stiffness of the wall by a large margin to obtain a stable solution and maybe then transfer to more flexible walls.



Thank you in advance,



P.S. additional data was left out to prevent bloat, but can be delivered on-demand
Attached Images
File Type: png Journal.png (41.8 KB, 1 views)
File Type: png Settings3.png (41.6 KB, 3 views)
File Type: png Settings2.png (16.9 KB, 2 views)
File Type: jpg file2.jpg (47.6 KB, 5 views)
File Type: jpg file1.jpg (51.2 KB, 3 views)

Last edited by Frisii; October 2, 2020 at 06:37. Reason: Edit to re-add attachements
Frisii is offline   Reply With Quote

Reply

Tags
2-way, ansys, biomechanical, fluent, fsi

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
1 way and 2 way FSI in ANSYS Workbench with Fluent and ANSYS Structural jwillie2000 FLUENT 6 November 27, 2017 00:21
Can't restart 2-way FSI using ANSYS 14.0 Workbench MSHowes ANSYS 2 July 3, 2014 14:30
FSI: How to transfer static pressure from fluent to ANSYS momo_sjx FLUENT 0 October 9, 2012 14:37
FSI, Fluent Ansys coupling Greg Carnie FLUENT 5 January 7, 2010 20:15
Properly using symmetry with both CFX and ANSYS workbench for a FSI analysis, help! Cirion0000 CFX 0 July 6, 2009 15:26


All times are GMT -4. The time now is 19:46.