Hi everyone,

I am currently building a disintegration effect using the Vellum Solver.

My Current Setup:

I have generated a velocity volume field (vel) that flows along several branching guide curves.

Inside the Vellum Solver (DOP network), I am using a POP Advect by Volume node (set to Match Velocity) to force the disintegrated vellum particles to strictly follow these branching paths.

The Goal & Problem:
While the particles follow the main path of the curves perfectly, they look far too stiff and linear. I want to add secondary organic motions—specifically, making individual particles orbit (spiral) around the curve's direction, or spin randomly as they travel.

I tried placing nodes like POP Axis Force and POP Force alongside the advection node. However, they don't respect the moving direction of the curves; instead, they apply forces based on the global axis or a fixed center point, which completely breaks the curve-following motion.

My Questions:

Is there a native POP node setup to make particles spiral/orbit locally around the advected volume's velocity vectors (treating the curve direction as the local axis)?

If I need to use a POP Wrangle, what would be the proper VEX logic to calculate a perpendicular rotation matrix based on the current vel or v attribute? (e.g., using cross() product with v to create an orbit/tangent force, or manipulating orient/omega for individual spin?)

What is the industry-standard approach for adding rich, micro-turbulent rotation to particles that are heavily constrained by a volume advection force inside Vellum?

I am using Houdini 21. I’ve attached a screenshot of my internal solver network below.

Any advice, VEX snippets, or node structure tips would be a lifesaver!