In both cases, a good starting point for setting up a new solver configuration is to right-click the study node and select Show Default Solver, then expand the
Solver Configuration tree under
Stationary Solver or
Time-Dependent Solver. Predefined iterative solver suggestions are automatically generated. Per default, a direct solver is used and two iterative solvers are suggested and disabled. To turn on one of these approaches, 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. Both suggestions are described below as well as how to set them up manually (in most cases the default suggestions should be used). In liquids where thermal effects can be neglected, the model can be solved in the adiabatic case and DOFs saved. Finally, choosing different shape functions can also reduce the memory consumption.
For large 2D problems and 3D problems, that only involve thermoviscous acoustics, using the following approach will save around 20% memory and can speed up the solution procedure by a factor 2 or 3. Under the Stationary Solver node take the following steps: Add an
Iterative solver with the GMRES solver. As preconditioner add the
Direct Preconditioner and switch the solver to PARDISO. Expand the
Hybridization section and select
Multi preconditioner in the
Preconditioner variables list add the
Pressure and
Velocity field. Add a second direct preconditioner with the same settings but now select only the
Temperature as preconditioner variables. The reason for splitting the equations up in this manner is that the energy equation is only loosely coupled to the momentum and continuity equations.
Start by adding an Iterative solver and select GMRES as the solver. Then right-click the iterative node and select
Domain Decomposition. A good starting point for this solver, is to use the default settings with only a few changes:
This is achieved by selecting the Adiabatic formulation option under the
Thermoviscous Acoustics Equation Settings section. When
Adiabatic formulation is selected, all temperature options and conditions are disabled in the user interface.
In models with a structured mesh, it can be advantageous to switch to the serendipity shape functions instead of the default Lagrange, see Lagrange and Serendipity Shape Functions below. In general, if a boundary layer mesh is used (to resolve the thermal and viscous boundary layers) or if a PML is used in the model, the mesh contains structured mesh regions.