Most common Turbulence models for shallow flows (2d)

Jaydi_21 · June 24, 2017, 19:12

Can you give me a short and brief explanation of the pros and contras of the most used models for shallow water flows? And if possible, some references, please?

I've been looking for some time now but I have not found something clear enough to me, as I'm new in this field.

ptemp · June 26, 2017, 18:01

The main thing you have to worry about with shallow water flow would be how the boundary layer affects the object of interest.

k-omega SST is usually the "go-to" since it includes the positive aspects of the k-epsilon as well as including good near wall treatment. Realizable k-epsilon used to be the go-to, but it requires higher mesh refinement near the wall. You can find the CFD-Online page on turbulence modeling below [1]. As a general statement, you can probably stick with k-omega SST while you're getting familiar with CFD. As you get more experience, you'll understand the models more.

[1] https://www.cfd-online.com/Wiki/Turbulence_modeling

Jaydi_21 · June 26, 2017, 23:46

Quote:

Originally Posted by ptemp

The main thing you have to worry about with shallow water flow would be how the boundary layer affects the object of interest.

k-omega SST is usually the "go-to" since it includes the positive aspects of the k-epsilon as well as including good near wall treatment. Realizable k-epsilon used to be the go-to, but it requires higher mesh refinement near the wall. You can find the CFD-Online page on turbulence modeling below [1]. As a general statement, you can probably stick with k-omega SST while you're getting familiar with CFD. As you get more experience, you'll understand the models more.

[1] https://www.cfd-online.com/Wiki/Turbulence_modeling

Do I still have to consider near the wall treatment for shallow flows? As I only a have a layer of fluid and depth averaged values? What do you mean by "the wall"?

ptemp · June 27, 2017, 11:03

Jaydi_21,

Well as with everything in CFD it depends on your boundary conditions. k-omega SST will work well with most cases. I don't see any reason why it wouldn't work for your case.

Walls are boundaries where a no-slip condition is applied. This means that the velocity on the wall is zero. With k-epsilon, layers of mesh (called prism layers or inflation layers) were needed to capture the gradient between the wall and the bulk flow. With k-omega SST, a blending function is used to model this gradient--hence less mesh refinement near the wall is needed.

I don't know the boundary conditions for your case, however I would recommend sticking with k-omega SST for now. Like I said, you'll understand more about turbulence modeling as you get more experience with CFD.

June 24, 2017, 19:12	Most common Turbulence models for shallow flows (2d)	#1
Jaydi_21 New Member Join Date: Jun 2017 Posts: 24 Rep Power: 9	Can you give me a short and brief explanation of the pros and contras of the most used models for shallow water flows? And if possible, some references, please? I've been looking for some time now but I have not found something clear enough to me, as I'm new in this field.

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June 26, 2017, 18:01		#2
ptemp New Member Paul Join Date: Feb 2017 Posts: 13 Rep Power: 9	The main thing you have to worry about with shallow water flow would be how the boundary layer affects the object of interest. k-omega SST is usually the "go-to" since it includes the positive aspects of the k-epsilon as well as including good near wall treatment. Realizable k-epsilon used to be the go-to, but it requires higher mesh refinement near the wall. You can find the CFD-Online page on turbulence modeling below [1]. As a general statement, you can probably stick with k-omega SST while you're getting familiar with CFD. As you get more experience, you'll understand the models more. [1] https://www.cfd-online.com/Wiki/Turbulence_modeling

June 27, 2017, 11:03		#4
ptemp New Member Paul Join Date: Feb 2017 Posts: 13 Rep Power: 9	Jaydi_21, Well as with everything in CFD it depends on your boundary conditions. k-omega SST will work well with most cases. I don't see any reason why it wouldn't work for your case. Walls are boundaries where a no-slip condition is applied. This means that the velocity on the wall is zero. With k-epsilon, layers of mesh (called prism layers or inflation layers) were needed to capture the gradient between the wall and the bulk flow. With k-omega SST, a blending function is used to model this gradient--hence less mesh refinement near the wall is needed. I don't know the boundary conditions for your case, however I would recommend sticking with k-omega SST for now. Like I said, you'll understand more about turbulence modeling as you get more experience with CFD.