Learning Forum

[a_l_o]

Hi folks,

I use Ansys Mechanical 2022 R2 to investigate pressure wave propagation in a Coupled Field Transient Analysis. As I want to simulate infinite behavior at the outer surfaces of my structure, i.e. no reflections, I used the condition "perfectly matched layers" (PML) for the outer "slice" of my structure (physics region set to "structural", geometry set to PML with APDL snippet "keyopt,matid,15,1"). Now I got an error and truncation:

If I am not allowed to use PML in a transient analysis: How do I inhibit pressure wave reflections at the outer surface of my solid structure? E.g., at one end of a pipe structure?

Thank you very much in advance!

[Bill Bulat]

I'm afraid that PML is only available for harmonic response analyses:

You can truncate structural media in transient analyses with a non-reflective boundary using INFIN257 which are created with the MAPDL EINFIN command:

Note however, that INFIN257 may only be used to trucate pure structural elements, not coupled field ones (SOLID226): I have a MAPDL example that works but am so far unable to get EINFIN to create INFIN257 elements with a command object in Mechanical. If I get that working I'll share images of the project with you (company policy forbides me uploading files to the Forum).

Best,

Bill

[a_l_o]

Hi Bill,

Your answer is really perfect, thank you very much! I am stilling looking into this matter at the side, so if you had any success in Mechanical, I'ld be glad if you share it here. I will also have look into INFIN257 elements!

Best regards,

alo

[Ushnish Basu]

Please note that transient elastic and acoustic PML is available in LS-DYNA:

https://lsdyna.ansys.com/pml/