[dylz]

I’m currently in the process of running a small project on the effect of an F1 front wing’s height in relation to the ground. I aim to demonstrate the effects of ground-effect, utilising Star-CCM+ to do this, I have already run domain and mesh independence studies.

I was hoping someone could confirm my current physics models etc. I am just a little unsure with these due to my wing geometry being so close to the floor wall boundary. This distance will vary between 1-10cm across 5 simulations.

Current physics models:
Constant Density, Gas, Gradients, K-Epsilon, RANS, Segregated Flow, Implicit Unsteady, Three Dimensional, Turbulent, Two-layer All y+ Wall Treatment, Wall Distance.

(I have not changed any of the default values used by these models).

Boundary Conditions:
Velocity Inlet: 60 m/s, Pressure Outlet: 0 Pa, All walls slip except for floor which has a tangential velocity set to 60 m/s.

I’ve seen various previous studies online which completed similar analysis using either K-Epsilon or Spalart–Allmaras. Any guidance on which turbulence model to use in this case? And if not these, any use in LES/DES?

Additionally, despite running a few of my own CFD projects over the last year I am still quite unsure about when to use Steady vs Unsteady models. I’ve read about the difference in the maths of the solvers, however, it’s still not clear to me what types of cases these should be used in. Could someone please give some simulation cases to help me understand when to each?

In summary:
1) Please check my Physics Models
2) Explain the difference between steady and unsteady simulations

Thanks very much!