CFD_external aero problems
Hi everyone,
i am new to ANSA and i am interested in making a CFD study of a simple car. In order to correctly predict separation regions i am using K-w SST model. For this to work i choose y+ 11 so the first height is 0.25mm. But when i create the layers all the cells of the road violate the aspect ratio criterion, even when i make it 100, and non orthogonality. Surface mesh of the car: min 5mm max 20mm Windtunnel: 5mm-300mm Sizebox_around_car: max surf:30 max vol:30 Sizebox_wake:max surf:40 max vol:40 I've tried many things such as making different layers for the road with first height cell 2.5mm but then i had skewed elements between the layers of the car and that of the road. I 'm interested in a 6-8 million cell mesh. Any advice about how to solve these problems and what are the best sizing for the mesh would be helpful. Thanks in advance, Argyris |
Hi Argyris.
Late reply, you've probably already solved the issue which I think doesn't have to do with ANSA. I think that the Aspect Ratio of the cells inside the boundary layer could be in the order of 10^3 not just 100. You can live with that I guess. If not, you can increase the number of points in the longitudinal direction but you'll end up with a massive cell count. Out of curiosity, why y+=11? It seems quite odd. I mean, if you are to use such a small value, why not go down to 1 as Menter suggests for his model? (even though the formulation in Fluent is supposed to be y+ insensitive. And also the underlying assumption is that you use fluent, right?) Best Regards, Lefteris Quote:
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