implement explicit algebraic stress model EASM
I have implemented an algebraic stress model for 2D turbulent flows near equilibrium in OF 1.6. It's implemented with an explicit formulation of the Reynolds-stresses and the equations are orginally from the paper: "Towards the developement of second-order closure models for non-equilibrium turbulent flows" from Charles G. Speziale and Xiang-Hua Xu. It's an explicit version of the SSG model.
Here's the link to the paper:
But it's a basic model for 2D flows near equilibrium solved with the equations 10, 13 and 14 of the paper. I implemented it with respect to the standard k-epsilon model, so you will need wallfunctions for k, nut, and epsilon, but not for the Reynolds-stresses.
You can download it here:
If you have any hinds, tips or ideas for improvement let me know.
I am just wondering whether you have looked into alternatives to the EASM you have used.
Other EASMs solve a non-linear equation for the production to dissipation ratio and hence avoid the singular behaviour in non-equilibrium flows. However, I am not sure how well they perform for strong non-equilibrium flows. Any Experience on that?
I have no big experience with EASM until now, but I hope this will change in future. In the next steps I want to implement other ASM, too, especially some for 3D ,non-equilibrium, low Reynolds flows and later with turbulent heat fluxes (Reynolds flux models).
I have tried to implement another ASM model from: "On explicit algebraic stress models for complex turbulent flows" from Gatski and Speziale, Journal of Fluid Mechanics. It's the regularized algebraic stress model on page 70.
Solving with this model a square duct you get the secondary flows at the edges, but they rotate with the wrong direction. The normal velocities nearby the walls are wrong. Maybe I need a boundary condition for them?
Changing -2(S_ik*S_kj) to +2(S_ik*S_kj) changes the secondary flows to rotate in right direction.
Has anybody an idea what's wrong?
Thanks very much, Thomas
convert to AnsysFlunet
Hi Thomas, I'm actually not very familiar with openfoam but I would like to use Ansys fluent for simulating a very similar case and if possible I would like you to convert the data file or even the mesh file ( that you linked here in the zip file) from Openfoam to Ansysfluent ..... thank you so much for your help :)
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