[Scientifix]

Hello everyone,

I am currentrly working on a project involving the meshing of a formula student race car ... but I do have issues with the mesh
It doesn't converge each time and when it does I have the following messages every iterration :

"turbulent viscosity limited to viscosity ratio of 1e05"
"reversed flow in the outlet"

Here are the settings I use (from https://www.youtube.com/watch?v=_4C7...ox3V0ib82t4drw) :

Right click on model -> Scoped sizing :

- BOI-far (around the whole car) : Min 1, Max 500, G-R 1.2, name : boi-far, Min 1, Max 50, G-R 1.2, selection : BOI-far.

- BOI-near (around the front/rear wings and the wheels): Min 1, Max 500, G-R 1.2, name : boi-near, Min 1, Max 10, G-R 1.2, selection : BOI-near.

- Wing-curvature : Min 1, Max 500, G-R 1.2, name : wing-curv, type : curvature, Min 1, Max 10, G-R 1.2, normal angle 9, scoped to : face zone, selection : wing.

- Wing-proximity : Min 1, Max 500, G-R 1.2, name : wing-prox, type : proximity , Min 1, Max 4, G-R 1.2, cells per gap : 3, scoped to : edge zone, selection : wing.

- Rod-curvature (around suspensions) : Min 1, Max 500, G-R 1.2, name : rod-curv, type : curvature, Min 1, Max 4, G-R 1.2, normal angle 9, scoped to : face zone, selection : rods.

- Wheel-curvature : Min 1, Max 500, G-R 1.2, name : wheel-curv, type : curvature, Min 15, Max 20, G-R 1.2, normal angle 9, scoped to : face zone, selection : wheel.

- Stand-curv (between wheels and road) : Min 1, Max 500, G-R 1.2, name : stand-curv, type : curvature, Min 1, Max 4, G-R 1.2, normal angle
: 9, scoped to : face zone, selection : stand.

- Chassis : Min 1, Max 500, G-R 1.2, name : chassis-curv, type : curvature, Min 10, Max 50, G-R 1.2, normal angle 9, scoped
to : face zone, selection : enclosure.

I then improve my surface mesh using Diagnostics->connectivity and quality.

I then mesh the enclosure with tet using the default settings and adding the option Grow prisms : scoped, name : wing-prism, offset method : last ratio, F-H : 0.02, number of layers : 10, last % : 20, Grow on : selected face
zone -> wing.

I set the boundary conditions (moving walls, rotating wheels ...) use Viscous model : k-omega, SST, curvature correction, production limiter.
I choose a coupled solver and run calculations.

Do you have better propositions on the meshing procedure and on the parameters I should use ? Everything seems to work fine in the video but fails when applied to my particular case...

Thanks a lot in advance for your help,
Scientifix

[LuckyTran]

Turbulent viscosity limited and reversed flow doesn't necessarily mean the mesh is bad, could just be a bad initialization and not running long enough to converge to the right solution.


My recommendation, start over. Mesh a plain box and run it until you get more familiar with the software(s) being used.