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Turbulence model for flow through a anechoic chamber

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Old   January 27, 2021, 12:05
Question Turbulence model for flow through a anechoic chamber
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Philipp Ziffer
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Hello everyone,

i want to simulate the flow inside of a anechoic chamber and I'm more interested in the flow in the middle of the 30m x 10m x 35 m chamber. But obviously i need to take the absorber wedges (height 300mm) on the wall into account. I would not be capable of modeling every single wedge. So after doing my research, I came to the conclusion, to assign the wall a specified roughness as an approximation.
Am i right, that in my case, the best turbulence model would be a k-epsilon RANS model, because i am not interested in the flow on the wall, rather how the roughness (wedges) affect the flow in the middle? I am quit a beginner, when it comes to CFD so I would appreciate some advice or literature.
While searching for a solution I just came across a lot of papers about ABL flows or flows in urban areas. Are there any similar to my problem?

The flow in the chamber is relatively slow with 0.2m/s and i would use pimpleFoam due to a pipe at the end of the chamber.

Thank you very much!
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Old   January 28, 2021, 09:48
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Petros Ampatzidis
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Hi Philipp,

In urban flows we substitute buildings/obstacles with surface roughness only when they are far away from the study area. In the study area, roughness elements are modeled explicitly. Theoretically, I think you can replace your wedges with surface roughness but you have to consult studies of similar scale.

Questions you might want to answer: i. To what extend do wedges mounted in the walls affect the air flow inside an an-echoic chamber? ii. What if I run a reduced scale precursor model with explicitly modeled roughness and then introduce it to my main model? iii. How does the size of the pipe affect the flow in the room?

I hope this might be a good start to think of your problem. Sorry if it's too vague.

Lastly, a relevant paper that might be helpful: An improved method for the estimation of surface roughness of obstacle arrays https://doi.org/10.1016/S1352-2310(97)00403-2

Best,
Petros
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