Learning Forum

[MarieLuise]

Hi,

I want to simulate the laminar-turbulent-transition in a channel flow with CFX in Ansys 2019 R1.

The channel is much wider than high, so I want to calculate this 2D.

I read the solver description for the gamma teta Model and it says that this is not valid for channel flows.

The One Equation Intermittency Transition Models solver description says that it is calibrated for classical boundary layer problems.

There are more than those two Transition Models to be selected in Ansys 2019 R1. (Special Intermittency, Gamma Model and Fully Turbulent)

Can somebody reccomend a suitable transition model for this problem (If possible, I would like to know the influence of wallroughness as well..)? 

 

Thank you!

[DrAmine]

All of transition models have been calibrated for non-channel flows. It is only valid for non-free shear layers and validated for classic boundary layers (wall attached flows). You can give the one equation intermittency a try but you would provably tune the transition onset equation.

[MarieLuise]

Thank you for your answer. 

How would you proceed to find out a sensible transition onset?

Are there guidelines or references for modelling this problem in Ansys?

 

 

[DrAmine]

Make a literature review and then I will decide what to do: that will be my first step.

On the same time I will just do some runs with the available options.