Tutorial: Using a File-Based Grid (Search Robustness)

Table of Contents

• 1. Initialize a Study
• 2. File-Grid Configuration
• 3. Run the Case
• 4. Visualize Results
• 5. Next Steps

This tutorial demonstrates grid.mode: file using the search_robustness template, which carries the only .picgrid the examples still ship.

Use file mode when the geometry already exists as a grid file and should stay fixed and explicit - a mesh from another tool, or one whose exact node positions are the thing under test. When the geometry is something the bundled generator can express, grid_gen says it in a few lines instead of a few megabytes; bent_channel moved that way once sweep could express a square duct through a quarter turn. See Grid Generator Guide: generators/grid.gen.

1. Initialize a Study

./bin/picurv init search_robustness --dest my_file_grid_run

Among the files it places:

my_file_grid_run/
|- search_robustness_curvilinear.yml
|- Imp-MG-Standard.yml
|- Search_Robustness_Output.yml
|- search_robustness_analysis.yml
`- bent_channel_coarse.picgrid

The grid is a unit square duct through a 90-degree bend, 21 x 21 x 145 nodes.

2. File-Grid Configuration

In search_robustness_curvilinear.yml:

grid:
  mode: file
  source_file: bent_channel_coarse.picgrid

Behavior:

• picurv validates the source grid file exists.
• Coordinates are non-dimensionalized before C execution using properties.scaling.length_ref.
• Generated normalized grid is staged into run config artifacts.

For geometric-periodic file grids, the runtime additionally verifies that each paired surface matches pointwise under one nonzero constant translation and that the periodic axis has at least four physical nodes.

3. Run the Case

./bin/picurv run \
    --case my_file_grid_run/config/case.yml \
    --solver my_file_grid_run/config/solver.yml \
    --monitor my_file_grid_run/config/monitor.yml \
    --post my_file_grid_run/config/post.yml \
    -n 4 --solve --post-process

4. Visualize Results

1. Open the recipe's .pvd under <run.visualization>/<recipe_id>/ if io.paraview_series.enabled is set. Otherwise open its numbered .vts files.
2. Use Stream Tracer seeded near inlet.
3. Color by Ucat_nodal magnitude.

This provides a fast sanity check of bend-flow behavior.

5. Next Steps

Proceed to Tutorial: A Guide to Visualizing Your Results.