Prism Layer (Boundary Layer) Thickness
i'm using the Star-CCM+ software to model a vehicle and a little confused about the prism layer thickness.
I know that the prism layer is to model the boundary layer, but the equation for boundary layer contains the Reynolds number. The Reynolds number changes at each point along the length of the car which will mean that the boundary layer will change.
Therefore, what should my prism layer thickness be as prism layer thickness can't change along the length of the car ..
Thanks in advance,
Calculate boundary layer for the end of the vehicle, set prism layet to capture that.
i.e. if you were doing a flat plate 1 m long, you would use "1 m" in your boundary layer calculation. Overkill upfront, but it ensures you capture it all.
I am also very new to Star CCM+ and this question has perplexed me too.. Even I am trying to figure out the logic behind the first prism layer thickness value, however the default values are 33 % of the base value. If your flow is laminar or highly viscous in the region of interest, you can reduce the value to 20% or even lower and use the all y+ wall treatment model with fine mesh around the region of interest. This model blends the viscous and turbulent profiles smoothly.
The finer mesh in the region of interest can be obtained by accessing the following in Star CCM+ Region of interest(Wall Type Boundary)> Mesh Conditions>Custom Boundary Growth Rate> Slow, Medium, Fast options are available you can choose among them depending upon your flow.
I hope this was useful
If my prism layer has 10 cells (for example) and the overall thickness of the prim layer is equal to the boundary layer thickness, do i still need to worry about y+ wall treatment or is it automatically taken care of?
|All times are GMT -4. The time now is 17:29.|