Tracing Multiple Spline Paths Through a CFD Velocity Field

You can create a shape composed of multiple splines by advecting a set of positions defined by an object's vertices through the velocity field of a CFD simulation.

1. Import a Simulation CFD file as described here.
2. Create a geometric object to define the starting positions for the advection, and move it into the desired position within the CFDImportData object. It can be any type of object with points, for example, you can create a plane or cylinder with the desired number of segments, or draw a line shape, and so on.
3. On the Create panel, select the Shape category and then select CFD.
4. Click CFDSplinePaths, and then click in a viewport.

   A CFDSplineNode object is created in the scene, temporarily represented by a circle.

5. Move the CFDSplineNode object to the world origin. In addition, make sure that it is aligned with the world and not scaled.
6. On the Modify panel, click the CFDImport Object button in the CFD Spline Paths rollout and then select the CFDImportData object in the scene.
7. Click the Paths Source button and then select the geometry object in the scene.

   Once both input objects are connected, the circle gets replaced by a shape consisting of multiple splines.

8. Set the other options as desired:

   Num Steps

   The number of vertices in the generated spline.

   Num Samples

   The number of nearby CFD data points to sample per vertex.

   Step SIze

   A divisor for the velocity vector used to extend the spline at each step. Values above 1.0 result in shorter, more accurate segments between spline vertices, while values between 1.0 and 0.0 result in longer segments.