Proposed Changes

Implementation of a new boundary condition for symmetry plane instead of using Euler Wall.
The implementation works as follows:

• Calculates new viscous eigenvalues for nodes in symmetry planes;
• Calculates new residuals to take into account the symmetry of the mesh; Only corrects momentum residual vector in current version.
• Uses a modified volume to calculate the solution in symmetry planes; Does not require modified volume in current version.

Related Work

#657

PR Checklist

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• I am submitting my contribution to the develop branch.
• My contribution generates no new compiler warnings (try with the '-Wall -Wextra -Wno-unused-parameter -Wno-empty-body' compiler flags, or simply --warnlevel=2 when using meson).
• My contribution is commented and consistent with SU2 style.
• I have added a test case that demonstrates my contribution, if necessary.
• I have updated appropriate documentation (Tutorials, Docs Page, config_template.cpp) , if necessary.

Results

For the sake of demonstrating the capability of the new Symmetry Boundary condition, the image shows a comparison of pressure at the surface, using the new implementation and the old symmetry boundary condition, for a flow over a 3D cylinder and considering the lateral and bottom surfaces as symmetry plane:

New Implementation vs Old Implementation for N2 mixture (2nd Order - NEMO_NS solver - AUSM scheme)

I have run this test without changing the viscous eigenvalues, and it converges to the same value. However, for unsteady simulations, changing the eigenvalues provides better results.

New Implementation (on NEMO) vs Current SU2 Implementation for AIR5 mixture (2nd Order - NS solver - AUSM scheme)