Reference / Input deck / model / fluid zones / rbf transform

rbf transform

type: rbf transform

Radial Basis Function transform fluid zone. Full RBF when base_point_fraction=1.0 (default), Multiscale RBF when base_point_fraction < 1.0.

support radius fixed zones basis base point fraction zonesrequired funcrequired

support radius

float·default 1·> 0

Support radius for interpolation

Guidance: Fluid–structure interaction →

fixed zones

list of int·not set by default

Zones held in place while the moving zones deform.

basis

default c2

RBF function type

Options

Value	What it does	When to use it
tps	A thin-plate spline in the distance scaled by `support_radius`; it is never zero, so the system is dense.	Small surfaces where a global, smooth deformation is wanted.
thin_plate_spline	Not implemented under this name; the run stops with an unknown-basis error.	Never; the thin-plate spline is `tps`.
multiquadric	Not implemented; the run stops with an unknown-basis error.	Never; use `c2`.
inverse_multiquadric	Not implemented; the run stops with an unknown-basis error.	Never; use `c2`.
gaussian	A Gaussian whose width is `support_radius`; it is never zero, so every pair of points interacts and the system is dense.	Small surfaces only, as the dense system grows with the square of the number of points.
linear	Not implemented; the run stops with an unknown-basis error.	Never; use `c2`.
cubic	Not implemented; the run stops with an unknown-basis error.	Never; use `c2`.
quintic	Not implemented; the run stops with an unknown-basis error.	Never; use `c2`.
c0	A Wendland C0 function that is zero beyond `support_radius`; the deformation is continuous but its slope is not.	Rarely; `c2` gives a smoother deformation with the same sparsity.
c2 default	A Wendland C2 function that is zero beyond `support_radius`, so only nearby points interact and the system is sparse.	The default, and the appropriate choice for most cases.
c4	Selects a Wendland C4 function, but the matrix assembly and the volume deformation evaluate `c2`, so the interpolation is inconsistent.	Not at present; use `c2`.
c6	Not implemented; the run stops with an unknown-basis error.	Never; use `c2`.

Guidance: Fluid–structure interaction →

base point fraction

float·default 0.2·> 0 and <= 1

Fraction of points to use as base points. 1.0 = full RBF, < 1.0 = multiscale RBF.

Guidance: Fluid–structure interaction →

zonesrequired

list of zone ids·required

Boundary zones the morph moves.

funcrequired

Python function·required·accepts a Python function

Function of the node position giving the deformed position of every surface node, called as f(*, location); it returns the deformed position as three numbers

Guidance: Python functions in the deck →