[ghastbug]

Background

So, I recieved a bunch of OF simulations from a colleague. They are 2D turbulent RANS komegaSST airfoil simulations. They are solved with simpleFoam, despite having an oscillating solution due to boundary layer separation vortexes.

As far as I understand, if you throw RANS at an airfoil, the unsteady turbulent eddy bits are averaged out, and we compensate that by making viscosity higher. So the solution over time becomes suddenly steady, and simpleFoam works, if you don't have more unsteady phenomena. But the boundary layer separation vortexes are unsteady, so I'm not sure if the simulation is valid.



I have attached an image of the force coefficients on the simulated airfoil per iteration. There you can see that if we put the airfoil at 0º, the solution is steady. However if we place the airfoil vertically at 90º, the solution becomes unsteady, because of flow separation.

Question: my colleage gave me simulations with oscillating solutions (view attachment, 90º plot), solved with simpleFoam. Since openFoam is a steady solver, is the solution valid?.


"Attachment": https://imgur.com/JJ7gGhB. (filesize too big to attach)https://imgur.com/JJ7gGhBhttps://imgur.com/JJ7gGhB