Calculation of drag on an ellipse


#1

Hello everyone,

I would like to calculate the drag of my ellipse with an extra shape in front.
Not having much knowledge in CFD, I work slowly using all possible help.
Today I think I have finished the mesh and the preparation of the simulation. However before starting the calculation, I would like to have the opinion of the community about my settings because I am not sure of everything.

The links to my project is as follows:

=> https://www.simscale.com/workbench/?pid=7732500420659620790#tab_0-0

Thank you in advance,
Julien


#2

Hi @julien_venture,

Is this supposed to be a 3D or 2D case?

Cheers.

Regards,
Barry


#3

Hi @Get_Barried,

I would like to make a 2D case.


#4

Hi @julien_venture,

You have a lot of nodes for such a small object. You might want to decrease the refinement at some points as you have over 8 million nodes now as the coarsest mesh which is still a little overkill. Ideally you’re looking at say a million nodes but you can afford extra nodes due to the computing power available.

Do note you should have a y+ of 30 to 200 for a wall function approach while for a full resolution y+ should ideally be less than 1 but LES is computationally very expensive so you might want to just use a wall function and stick to the less expensive y+ of 30 to 200. I see that you’ve done a proper BL inflation for Mesh 3 so lets see how that goes.

If you want to significantly decrease the number of nodes and increase simulation time I suggest doing what I’ve done here for my compressible project and using Tet mesh with an extruded plate containing a hole that represents your shape instead. Although note that I’ve been running into strange problems with compressible flow but it doesn’t hurt to try.

Cheers.

Regards,
Barry