Efficient computational simulations are vital for optimizing design processes. Here are several strategies to reduce computation time while maintaining accuracy, organized into three key areas: Geometry, Physics, and Meshing.
Geometry
Simplification
Simplifying your model’s geometry is an effective way to speed up simulations. Remove unnecessary details like small fillets, tiny holes, or intricate patterns that have minimal impact on results but greatly increase computational effort. Read more in article “What makes a good CAD geometry“.
Delete repeating geometry
If your geometry consists of more than one identical workpiece-conductor system, select one to simulate and delete the others.
Simulate only half
If you have geometry of linear symmetry, simulate only half of it and mirror results to represent the whole geometry.
Use 3D slice
If you have axial symmetric geometry, cut out and simulate one repeating sector of it, for example, one tooth from a whole gear, then revolve results to represent whole geometry.
Make 2D from 3D
For revolved geometry there is no need for 3D simulation, simulate only plane slice from full geometry and revolve results to represent the whole geometry.
Physics
Time step size
- To balance accuracy and efficiency, consider using an adaptive time step, which automatically adjusts the step size based on the rate of temperature change, ensuring optimal performance throughout the simulation.
- Using an excessively small time step can lead to inaccurate results and significantly increase computational time. If the time step is too small, you may notice in the iteration window that convergence occurs after just one iteration. This happens because the thermal change between steps is minimal, causing the solver to accept the initial calculation as converged without allowing further adjustments through multiple iterations. As a result, the simulation may not properly refine the solution, potentially compromising accuracy.
- Use time step table. If you want to resolve the initial heating better, but don’t want to use Adaptive time step (to keep the control over how many time steps will be calculated), you can define the time step size in a table and make the step size smaller in the very beginning of the heating, and then increase it to save calculation time.
Steady-State calculation
Whenever possible, switch to a steady-state calculation instead of a transient simulation. Steady-state model is much faster as they do not require solving for time-dependent variables. This approach is useful when the main interest is in the equilibrium state of the process.
Material properties
Using accurate but simplified material properties can also reduce computation time. For instance:
- Avoid B-H usage if possible: For certain simulations, replacing B-H curve with constant magnetic permeability can save time. Before changing to constant permeability it should be tested where results with BH curve and constant magnetic permeability are compared to yield the same results. In many cases it is possible to switch to constant permeability and speed up simulation significantly.
Stranded/Litz wire
If your simulation involves inductors or coils, representing the conductor as a stranded or Litz wire simplifies the model by avoiding detailed meshing of individual wires. This approach captures the essential behavior of the coil without requiring the computational complexity of modeling each strand. Read more in article “Defining stranded or litz wire inductors“.
Meshing
Reducing mesh size
Mesh refinement significantly affects computation time. To optimize the mesh:
- Use Coarser Mesh in Non-Critical Regions: Apply fine meshes only in areas with high gradients, such as near boundaries or regions of interest. Use coarser meshes in uniform regions to reduce element count.
- Curvature and Volume Gradients: Adjust curvature safety and volume gradients to reduce unnecessary refinement in less critical areas, particularly around smooth curves or in large homogeneous volumes.
- Simplify Skin Layers: For simulations involving skin effects, reduce the number of skin layers and adjust skin depth based on calculated requirements.
Read more about meshing tips and tricks here.
