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 mb.pejvak April 17, 2012 23:47

boundary and initial condition for SST k-omga turbulence model

Hi everyone.

I am writing self-developing code and I want to apply SSt k-omega turbulence model for simulation of flow over a flat plate. but I can't find any good references that has and explains boundary and initial conditions for external flow. I find some that have different boundary, esp. for inlet and far-filed. for example, in some references propose that viscosity ratio (Mut/Mu) should be between 1 and 10 and also turbulence intensity and using these two, value of k and omega in inlet can be calculated as follow:

Inlet:
(kinlet=1.5*(turbulence intensity*free stream velocity)^2 ,
Mut=(1-10)*Mu
omegainlet=ru*kinlet/mu*viscosity ratio)

far field boundary:
Omegainf>10*free stream velocity/L L: characteristic Length
Mutinf<10e-2*Mutmax
Kinf=Mutinf*omegainf/ru

but I should mention in some paper constant numbers are different. in some paper or user's guide suggest that turbulence intensity set between 1-10%.

My problem is these boundary layer is correct and how can specify viscosity ratio and turbulence intensity in specified Re?
And if any good reference explain it, I really appreciate letting me know.

 DoHander April 18, 2012 20:26

Turbulence modelling for CFD by Wilcox:

http://www.amazon.com/gp/product/192...SIN=1928729088

 mb.pejvak April 19, 2012 01:28

Thank you so much DoHander.
I read the book that you introduce, but I can find any boundary condition for inlet and freestream in external flow.
Are you sure these boundary conditions were introduced in the book? and if yes, could you please tell me which part of this (I know in part 7.2.2 was talked about turbulent/non-turbulent interfaces, But boundary conditions were not introduced).

Thank you.

 mb.pejvak May 1, 2012 20:06

I found a good paper "Effective Inflow Conditions for Turbulence Models in
Aerodynamic Calculations" by Spalart and Rumsey that explained inflow boundary condition for SST k-omega and SA turbulence models and also they recommended inflow boundary condition for these two models.

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