How do I define where refinement should occur with SPH Adaptive size in Ansys FreeFlow?

[FAQ]

How do I define where refinement should occur with SPH Adaptive size in Ansys FreeFlow?

Ansys FreeFlow provides three approaches for defining refinement regions:

1. Geometry Boundary Refinement

Refinement is applied based on proximity to selected geometry boundaries (walls).
You specify:

• A Refinement Distance Factor
• A Refinement Level

A refinement zone is computed as:

Refinement Distance = Refinement Distance Factor × Initial SPH Size

All SPH elements within this distance from the selected geometry are refined. The refinement region is subdivided into volumes proportional to its size, with refinement levels that increase gradually across these partitions. The figure below provides a schematic representation of this process.

2. Cubic Region of Interest (ROI)

You define a cube-shaped region in space. All SPH elements inside the cube are refined according to the selected refinement level.
This approach is useful for localized flow features such as impacts, mixing zones, or free surface interactions.

3. Cylindrical Region of Interest (ROI)

You define a cylindrical region in which SPH elements are refined.

• If no hole ratio is specified:
  • All elements inside the cylinder are refined
• If a hole ratio is specified:
  • Only elements outside the hole region are refined

This is particularly useful for pipes, jets, nozzles, and axis-aligned flow features. The user can combine different ROI geometries and set one refinement level for each ROI.

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Ansys FreeFlow™ smoothed-particle hydrodynamics (SPH) simulation software