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-   -   Problem w/ vortex ring simulation, mesh coarseness parameters? (https://www.cfd-online.com/Forums/fluent/95490-problem-w-vortex-ring-simulation-mesh-coarseness-parameters.html)

 ESC December 20, 2011 05:25

Problem w/ vortex ring simulation, mesh coarseness parameters?

Hey, having an issue with my FLUENT simulation that I hope I can get some feedback on!

My mesh is an axisymmetric 2D model where, in the rotated form, a cylindrical capsule with a cap is in a region of air, with a pressure difference inside the capsule (e.g. 2atm gauge). The simulation starts, and the pressure difference causes the cap to blow off, and a vortex ring to form.

I've been measuring how the distance that the vortex ring travels varies depending on various factors (e.g. pressure difference, cap weight (controlled by UDF), etc) and tried varying the mesh coarseness (triangular mesh). I've found that as the mesh is made more fine, the vortex rings also travel further, making the distance traveled diverge as mesh fineness increases. This is the opposite of what I would hope.

I haven't been changing any of the FLUENT parameters between the coarse mesh and the fine mesh, and the simulations have run alright, but are there things that I should be altering according to mesh coarseness, or is there something that I'm forgetting to do? Any input is totally welcome.

I'm using the LES turbulence model.
Mesh diagrams and more information available on request, sorry if my explanations aren't as detailed as they can be!

Thanks!

 qing123 September 4, 2012 08:06

Hi ESC: Have you solved your problem? Maybe I can help you, because I have just completed one project correponding to the vortex ring. But I could not fully understand your questions. Could you send me model file to me adding some descriptions, hope to give you some useful suggestions. My email is: 1402891092@qq.com

 ESC September 4, 2012 10:56

Hello! Yeah, this problem was resolved. Thank you for the offer of assistance, though!

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