Expert Parameters
ultraFluidX 2021.1 features additional expert parameters, that can be used to fine-tune the simulations.
When these parameters are not specified, established default values are applied. Moreover, the expert parameters then do not show up in the effective solver deck.
- <simulation> - <general> - <num_ramp_up_iterations>
- By default, the mean velocity at the inlet is increased from 0 to the requested value over a certain amount of physical time. Using this parameter, you can also explicitly specify a fixed number of coarsest iterations for the ramp up.
- <simulation> - <general> - <convergence_detection>
- Activates the ultraFluidX convergence detection algorithm output (still in beta mode). The algorithm analyzes the transient drag and lift signals and estimates if and when the initial transient phase has ended and when the overall simulation has converged; the respective iteration steps are reported in the uFX_summary.txt file, together with averaged force coefficients that are determined between these two points in time
- <simulation> - <geometry> - <triangle_mesh_export>
- If this parameter is set to true, the triangulated surface used in the code (after triangle_splitting, if applicable) is exported to uFX_meshData/uFX_surfaceMesh.stl.
- <simulation> - <wall_modeling>
-
- <wall_model_intensity>
- The wall model intensity parameter is used together with the <coupling> “one-way” option and determines the strength of the link between the velocity taken as input to the wall model and the information fed to the first near wall cell. For a value of 0.0, the wall model is effectively switched off and a standard no-slip boundary condition is applied.
- <donor_interpolation>
- The donor position is the point where the wall model is coupled to the flow field, in a sufficiently well resolved part of the boundary layer. This donor position does not necessarily coincide with a voxel center; the information required at this position will be interpolated/derived from the data available in the 27 voxels (3x3x3) around the donor position.
- <meshing> <general> <seeding_point>
-
- <x_pos>, <y_pos>, <z_pos>
- The seeding point is the position in the domain from with the flow region is filled with “fluid” voxels. By default, this position is placed at one of the corners between the inlet plane and the ground.