[alimea]

Hi all
I want to solve this problem:

3D incompressible flow of air around the axis of a cylinder in Ma=0.2.

1-which turbulence model (or models) is better? what is in priority?

2- could you plz help me for chosing appropriate boundary conditios?
ecpecially for pressure. because this problem is in p_inf = 30 kPa. should I set the up, down, outlet, front and back in 30 kPa? or that is not important and it can be every value?
In a tutorial in openFoam that is for a 3D airFoail I saw that they set freestreamPressure! what is that? Also they set inlet and outlet (the right hand side of my geo in pic) velosity the same! why? should I set them the same for my problem? I think that is wrong and I must allow the code to calculate it!

3- Is it correct to do it with simpleFoam for turbulent and icoFoam for laminar regim in openFoam?

http://uupload.ir/files/gez0_untitled.png

Thank you so much

[Waqar.Mehdi]

Hello

I am currently doing a project regarding analysis on airfoil of Vertical axis wind turbine , I have already researched about many turbulence models like realizable K-epsilon , RNG K-Epsilon, spalart allmaras and K-Omega SST but which should i select and on what basis. Please help me about this

[TheVictorVS]

Originally Posted by Waqar.Mehdi

Hello

I am currently doing a project regarding analysis on airfoil of Vertical axis wind turbine , I have already researched about many turbulence models like realizable K-epsilon , RNG K-Epsilon, spalart allmaras and K-Omega SST but which should i select and on what basis. Please help me about this

I agree, although if you have read the least about those models and you should have a concrete idea about the model that you can use in your project, describe what you need with precision

[Waqar.Mehdi]

Originally Posted by TheVictorVS

I agree, although if you have read the least about those models and you should have a concrete idea about the model that you can use in your project, describe what you need with precision

Yes! i am really confused but i think i need precison in pressure gradient but what i need is the pros and cons of these so that it becomes convinient for selection.

[TheVictorVS]

Originally Posted by Waqar.Mehdi

Yes! i am really confused but i think i need precison in pressure gradient but what i need is the pros and cons of these so that it becomes convinient for selection.

hummm no, sorry that is not correct, what I mean is that in the literature that you should have reviewed, you will have detailed the approach that each model of turbulence uses, for example the k-epsilon model is to describe free flow and flow without a high degree of internal disorder, the model K-epsilon realizable, is the same as the previous one only that this allows to scale the effects of the turbulence dynamically to reach greater precision, the K-omega is able to describe turbulent flows with greater degree of disorder or anisotropy than the previous ones, but it is also capable of resolving the flow of fluid to the domain wall, something that the previous 2 models only calculate in a rough way with a relationship called wall functions, they suppose they do not really calculate it , and the omega SST model is a combination of the K-epsilon and k-omega strengths, but it is not necessarily better because what the model really does is to alternate between the two formulations. But that choice is made arbitrarily, and when I asked you what you needed was if you need the flow to resolve to the wall, is it possible to see your flow showing strong turbulence, although from the above you want to model something like a centrifugal pump?