Karman Vortex 2d- laminar

qutadah.r · June 26, 2022, 08:21

I am trying to simulate air flow around the cylinder in 2d.. The flow is laminar (Re= 100) and I am using pimpleFoam.

I am not sure what to use for my BCs for the patches... I have used slip for the cylinder in this simulation. I think it is wrong.

Second, the flow does not look exactly correct right?

Any help would be appreciated.

Here is a video of the simulation!

https://drive.google.com/drive/folde...vr?usp=sharing

A photo is also uploaded!

Thanks!

ngbidi · June 27, 2022, 12:33

Dear qutadah,

can you provide more information on the case? Did you try higher Reynolds numbers?

qutadah.r · June 27, 2022, 15:08

Hello,

I have used instead pimpleFoam (kindly read the problem description again, I have uploaded a video of the simulation).

Thanks ! I actually only tried it for Re 100, and as described the flow shouldnt be oscillating at the downstream of the cylinder at that Reynolds number right?

Thanks!

Santiago · June 28, 2022, 03:57

Quote:

Originally Posted by qutadah.r

I am trying to simulate air flow around the cylinder in 2d.. The flow is laminar (Re= 100) and I am using pimpleFoam.

I am not sure what to use for my BCs for the patches... I have used slip for the cylinder in this simulation. I think it is wrong.

Why you use 'slip' for a highly viscous problem?

joshwilliams · July 6, 2022, 12:07

I cannot see any issue in the flowfield visualisation picture you show. (I did not view the video). It is oscillating, as flow over a bluff body should. You should use more quantitative way to verify if it is working or not. There will be a lot of literature for drag coefficient or other metrics for flow over a cylinder.

To echo what Santiago is implying: unless there is a key detail in your problem setup or objectives that you have excluded, I would recommend using noSlip on the cylinder walls. Outlet should be zeroGradient for velocity (or inletOutlet for improved stability). Outlet for pressure should probably be fixedValue or totalPressure.

June 27, 2022, 12:33		#2
ngbidi New Member Join Date: Mar 2022 Posts: 6 Rep Power: 4	Dear qutadah, can you provide more information on the case? Did you try higher Reynolds numbers? Last edited by ngbidi; June 27, 2022 at 12:44. Reason: further specify the question

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June 27, 2022, 15:08		#3
qutadah.r Senior Member qutadah Join Date: Jun 2021 Location: USA Posts: 101 Rep Power: 4	Hello, I have used instead pimpleFoam (kindly read the problem description again, I have uploaded a video of the simulation). Thanks ! I actually only tried it for Re 100, and as described the flow shouldnt be oscillating at the downstream of the cylinder at that Reynolds number right? Thanks!

July 6, 2022, 12:07		#5
joshwilliams Senior Member Josh Williams Join Date: Feb 2021 Location: Scotland Posts: 112 Rep Power: 5	I cannot see any issue in the flowfield visualisation picture you show. (I did not view the video). It is oscillating, as flow over a bluff body should. You should use more quantitative way to verify if it is working or not. There will be a lot of literature for drag coefficient or other metrics for flow over a cylinder. To echo what Santiago is implying: unless there is a key detail in your problem setup or objectives that you have excluded, I would recommend using noSlip on the cylinder walls. Outlet should be zeroGradient for velocity (or inletOutlet for improved stability). Outlet for pressure should probably be fixedValue or totalPressure.