[Gaëtan47]

ok, I have started to do this sensitivity analysis (but I'm kind of reaching my maximal computing capacity...).

The result is pretty stable, lift and drag point of view. But still, I need to implement a correct wall function.

Do you know what are the parameters that I should use for my case in the domain definition? (see screenshot).

I have seen on the ansys help, and in one of your previous post, that gamma theta option with SST solver is the most suitable for blade turbines... but what about all the other options? (viscous term, high speed, turbulent flux closure, transitional turbulence, intermitency coefficients, retheta....)


Thank you for your help

[ghorrocks]

My suggestions:

* Use the default SST turbulence model unless you have a good reason not to.

* Do a mesh sensitivity study to determine the first element size which works for your case. Do not assume you need a y+=1 mesh (unless you have a good reason to think so)

* The turbulence transition model is available, but only use it if turbulence transition is going to have a significant effect. It will increase the difficulty of the simulation a lot, so only use it if you really have to (you will definitely need a y+=1 mesh, stricter mesh requirements along length of foil, possibly need transient simulation)

[Gaëtan47]

hello,

I have now a good mesh for my application, results are stable and I get a correct convergence of the calculation.

However, I cannot simulate the experimental conditions which are at the inlet: 100m/s, 1bar, 650K (density=0.33777kg.m-3).

Which boundary condition should I use to fix the velocity AND the pressure?


I have tried to use a mixed flow regime and set the option "pressure and velocity" (see screenshot "speed and pressure"). But this gives me an immediate compression and slow down of the flux just after the inlet (screenshot "compression"). So this is not working.

Also I have tried to use "total pressure (stable)" inlet, thinking that the pressure would have change only the velocity and not the static pressure, but both are increasing when I increase the total pressure.... (however the stability of the inlet is good here).


Do you have an idea on how I can solve this?

Thank you in advance.

[Gaëtan47]

and the output file

[ghorrocks]

You cannot fix the velocity and pressure at a boundary. If you know the velocity then you probably know the flow rate. Then you can apply a type of pressure boundary at the inlet and a type of mass flow/velocity boundary at the outlet.