fsi
Fluid-structure interaction model that couples this wall's motion to a structural solve.
RBF support radius, also the mode-shape deformation scale used when normalising mode shapes for morphing
Zones held in place while the moving zones deform.
RBF function type
| Value | What it does | When to use it |
|---|---|---|
| tps | A thin-plate spline in the distance scaled by | Small surfaces where a global, smooth deformation is wanted. |
| thin_plate_spline rbf_multiscale only | Not implemented under this name; the run stops with an unknown-basis error. | Never; the thin-plate spline is |
| multiquadric rbf_multiscale only | Not implemented; the run stops with an unknown-basis error. | Never; use |
| inverse_multiquadric rbf_multiscale only | Not implemented; the run stops with an unknown-basis error. | Never; use |
| gaussian | A Gaussian whose width is | Small surfaces only, as the dense system grows with the square of the number of points. |
| linear rbf_multiscale only | Not implemented; the run stops with an unknown-basis error. | Never; use |
| cubic rbf_multiscale only | Not implemented; the run stops with an unknown-basis error. | Never; use |
| quintic rbf_multiscale only | Not implemented; the run stops with an unknown-basis error. | Never; use |
| c0 | A Wendland C0 function that is zero beyond | Rarely; |
| c2 default | A Wendland C2 function that is zero beyond | The default, and the appropriate choice for most cases. |
| c4 | Selects a Wendland C4 function, but the matrix assembly and the volume deformation evaluate | Not at present; use |
| c6 rbf_multiscale only | Not implemented; the run stops with an unknown-basis error. | Never; use |
Fraction of points to use as base points
Structural file format
| Value | What it does | When to use it |
|---|---|---|
| nastran | Reads the structural grid from | Always; it is the only format supported. |
Nastran case name (without extension)
Scaling factors [x, y, z]
Max distance for mode mapping
Inverse-distance power for mapping mode shapes to the surface
Use pure inverse-distance weighting for the mode mapping
Number of nearest structural points used per surface point
Deformation fraction of the RBF support radius at which the base-point set is rebuilt; 0 never rebuilds it
Newmark integrator alpha parameter
Newmark integrator delta parameter
Cycles between structural updates: the modes are marched and the mesh deformed once every this many solver cycles. With several modal models the smallest value applies to all of them.
Scaling factor for fluid forces
List of modes to include
Damping factors for each mode
The structural coupling: modal_model uses the built-in Nastran modal model, generic_fsi couples to an external structural solver.
| Value | What it does |
|---|---|
| modal_model | Selects the built-in Nastran modal-model coupling. |
| generic_fsi | Selects the generic external-solver coupling. |
Mesh deformation transform used for the coupling
| Value | What it does | When to use it |
|---|---|---|
| rbf_multiscale | Deforms the volume mesh using the multiscale RBF scheme. | |
| idw | Deforms the volume mesh using inverse distance weighting. | |
| rbf | Deforms the volume mesh with a single-level RBF, adding surface points one at a time, worst-interpolated first, until each is within | Where an error-controlled choice of points is preferred to the fixed |
Power parameters for IDW
Maximum stencil size (number of nearest neighbors)
Number of nearest points for IDW
Maximum deformation distance
Blending stiffness parameter
Zone IDs coupled to the external solver
RBF solve tolerance
Maximum allowed RBF interpolation error
Arbitrary variables passed to the external coupling solver (genuinely open-ended — not enumerable).