Choice of LES Turbulent Models in OF

tayo · February 18, 2013, 15:24

Hello all,

Please I have some rather broad questions on LES models in OpenFoam. Kindly help answer any or all of the question(s) if you can. Thank you.

1) What LES model would be better for a two-phase flow with Reynolds number of O(10^5) and why? (I currently have oneEqEddy, Smagorisky, vanDriestDelta and spalartAllmarasDDES in mind).

2) What's the criteria for changing values of nuSgs, nuTilda, k, and B in the BCs?

3) What's the advantage of using a dynamic model (e.g. dynOneEqEddy over oneEqEddy)? Since I have a dynamic meshing in my solver, does it mean I have to use a dynamic LES model?

4) In my energy eqn, I have k_eff = k_laminar (2-phase) + k_t
k_t = nut()/Prt. Prt is the artificial turbulent Prandtl number defined as nut()/thermal-diffusivity. It is between (0.7-0.9) for water right? Using Prt just like nut() tells you that Prt is undefined when you compile. How do I find this Prt in 2-phase solver in OF? I currently have it defined as 0.85 in my TEqn but how to I locate and use it in OF but as nut() is applied.

tayo · February 21, 2013, 00:07

Ok. Question 4 has been answered. I had to use an experimental correlation from the literature to obtain my two-phase Prt as a function of Pr.

However, I still waiting for answers to my other questions. Thank you.

sihaqqi · April 16, 2013, 23:27

If you have found answers to other questions you asked, can you please post. I am a starter in CFD and I have to do LES of air flow in pipe elbow. I want to know how can I calculate values of B and nuSgs to put in my dictionary. do you have knwledge about the formulae.

February 18, 2013, 15:24	Choice of LES Turbulent Models in OF	#1
tayo Member Tayo Join Date: Aug 2012 Posts: 94 Rep Power: 13	Hello all, Please I have some rather broad questions on LES models in OpenFoam. Kindly help answer any or all of the question(s) if you can. Thank you. 1) What LES model would be better for a two-phase flow with Reynolds number of O(10^5) and why? (I currently have oneEqEddy, Smagorisky, vanDriestDelta and spalartAllmarasDDES in mind). 2) What's the criteria for changing values of nuSgs, nuTilda, k, and B in the BCs? 3) What's the advantage of using a dynamic model (e.g. dynOneEqEddy over oneEqEddy)? Since I have a dynamic meshing in my solver, does it mean I have to use a dynamic LES model? 4) In my energy eqn, I have k_eff = k_laminar (2-phase) + k_t k_t = nut()/Prt. Prt is the artificial turbulent Prandtl number defined as nut()/thermal-diffusivity. It is between (0.7-0.9) for water right? Using Prt just like nut() tells you that Prt is undefined when you compile. How do I find this Prt in 2-phase solver in OF? I currently have it defined as 0.85 in my TEqn but how to I locate and use it in OF but as nut() is applied.

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February 21, 2013, 00:07		#2
tayo Member Tayo Join Date: Aug 2012 Posts: 94 Rep Power: 13	Ok. Question 4 has been answered. I had to use an experimental correlation from the literature to obtain my two-phase Prt as a function of Pr. However, I still waiting for answers to my other questions. Thank you.

April 16, 2013, 23:27		#3
sihaqqi Senior Member starter Join Date: Sep 2012 Posts: 125 Rep Power: 15	If you have found answers to other questions you asked, can you please post. I am a starter in CFD and I have to do LES of air flow in pipe elbow. I want to know how can I calculate values of B and nuSgs to put in my dictionary. do you have knwledge about the formulae.