## Fluids

#### FSI transient response

• sblee
Subscriber

Hello,

I want to do a transient FSI simulation to investigate the structural response out of changed fluid pressure input. In a L shaped pipeline, for example, where inlet/outlet pressure is 50 psi uniformly, I want to have a sudden increase of inlet pressure to 80 psi (and no change of outlet pressure). I want to review the transient structural response (e.g., y directional displacement at the cornered area ). Do we call this as "pressure shock?" Thanks.

• Karthik R
Hello Yes, you should be able to do this using the System Coupling in Ansys Workbench. You will need to couple Ansys Mechanical and Fluent (or CFX). There are some tutorials on how to set up such problems in Ansys Help. Here is the link.
Examples: https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v211/en/sysc_tut/sysc_tut.html
Files: https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/prod_page.html?pn=System%20Coupling&prodver=21.1&lang=en
Karthik
• sblee
Subscriber
Karthik Thank you for your comment. I know how to do a basic FSI. The point of my question is about how to apply a "sudden pressure rise/drop (step function)".
In CFX, seems like we only can apply a "static" pressure condition as below.

• sblee
Subscriber

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Min ZhangDalian University of Technology, ChinaPosts:20MemberNovember 2017edited November 2017Flag
I have not ever performed transient simulations, but two methods may help.
1 you can create an Expression if the Pressureis a function of the timet. eg. P=101325[Pa]+10[Pa/s]*t (notice the unit)
2 your can set the inlet pressure profile usingUser Fortran. I just learned something aboutCFX User Fortran. It can obtain the transient information, set the boundary profile and so on.
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• Karthik R