low Reynolds Model for pipe flow
Dear Community,
i would like to simulate a pipe flow with has a low Reynolds  Number. Does someone know, what lowReturbulencemodel is best for? I already tried using LaunderSharma KE  it works with only 2% difference from u_max in comparison with HagenPoiseuille  but i do not know, if LaunderSharmaKE was developed for such applications. So does someone know about this? I am using the simpleFoam solver! Greetings Martin 
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Martin, it is a pitfall: A LowReynolds turbulence model is NOT designed for low reynolds numbers. It is designed for resolving the near wall layer without wall functions. Therefore, you need to create your mesh different if you use a lowRe model compared to a HiRe model. I suspect for a pipe flow with modest separations a HiRe model should be sufficient. However, you have to make sure your mesh fits for a HiRe model. Regards Bastian 
Is there a tutorial of LaunderSharma, I want to copy their files, however, the files of LaunderSharma should be almost the same as the k epsilon.

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I need to resolve the near wall layers without wallfunctions!
The ReynoldsNumbers vary between 150 up to 320... I do not think, that a high Re  Model is able to solve the flow right! My pipe has a diameter of 0.004 m  in fact it consists only of near wall layers ;) i also added a picture showing my grid and one which shows the velocity field, that kOmegaSST Model offers in comparison to HagenPoiseuilleprofile! Martin 
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If you still want to run a low Reynolds model (even though it is not necessary) you need to have a much lower thickness of the first cell next to the wall. The appropriate value of this can be estimated with the y+ value. Regards Bastian. 
Hi Martin,
You mesh look quite nice. Just want to ask that did you use transfinite progression stuff to make the layers at boundary more denser than those away from boundary? Thanks a lot. 
Hi Eren,
You can lookup nacaAirFoil tutorial but it's for compressible case though. Otherwise, you always can look for launderSharma codes from Doxygen. Regards, Robert 
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Laminar is probably the way to go. Just my thoughts, and if anyone disagrees with my conjecture, please include your thoughts. 
Dear Bastian,
what y+ value do i need? My calculations actually run with y+ avg of 0.8... is this to high? @ Martin: maybe laminar seems to be the best way... it was a test with lowRe... In fact, LaunderSharmaKE gives out great results. I will also calculate all my cases with laminar flow and compare them with LaunderSharmaKE. For information: LaunderSharmaKE was originally designed to solve the flow and heat / mass transfer near a rotating disk. @ liguifan: i used meshGrading with blockMesh to make the cells finer at the wall. 
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I also have another question:
i am calculating the flow through bend pipes, to get to know about the wall shear stress: Does someone have an idea, how i could get wall shear stress in cylinder coordinates from a result, that gives out Cartesian ones? The aim is, to get a chart, which shows the wall stress in dependence from pipelenght... maybe the pictures will make it clearer! The chart is only an example! Thank you very much for your answers! Martin 
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