Solver Suggestions for Large Aeroacoustic Models
Studying aeroacoustic applications often lead to very large models that can contain many degrees of freedom (DOFs). Different steps can be taken to reduce the models size, for example, consider the use of slip instead of no-slip conditions in the LNS interface (avoiding the details in the acoustic boundary layer) or consider the choice between Lagrange and Serendipity Shape Functions.
When a model reaches a size where it can no longer fit in memory (when solved using the default direct solver) or if the solution procedure is slow with a direct solver, then it can be advantageous to switch to an iterative solver approach.
For the Linearized Navier-Stokes interfaces iterative solver suggestions are automatically generated when the default solver is generated. These can be seen by expanding the Solver Configuration tree under Stationary Solver or Time-Dependent Solver. Per default a direct solver is used and two iterative solvers are suggested and disabled (grayed out). To turn on one of these approached right-click the solver and select Enable (or press F4). The first suggestion (GMRES with Direct Precon.) uses an iterative solver with a direct preconditioner. This method is typically faster then the direct solver and uses 20% less memory. The second suggestion (GMRES with DD) uses an iterative solver with the domain decomposition method. This method is very robust (also for multiphysics applications) and very memory efficient, but it can be slow.
Further details on solving large models can be found in the Solver Suggestions for Large Thermoviscous Acoustics Models section. These suggestions also apply fir the linearized Navier-Stokes physics.