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Computational Fluid Dynamics (CFD) Videos


How to apply different initial values (initialization) to different areas of a mesh in ANSYS Fluent

In this ANSYS Fluent Tips & Tricks video, we show how different initial values (initialization) can be applied to different areas of a mesh. The standard initialization populates the mesh with a constant initial value everywhere. This is not always desirable. For example, having different values in different areas of the mesh would be especially useful for cases with multiple bodies start at different temperatures, or free surface flows where certain areas start with liquid and others start with air.

Although User Defined Functions (UDF’s) can be used to do this through the define_init macro, for simple cases UDFs are overkill. As such, functionality in the Fluent GUI called “Patch” can be used to achieve different initial values in different areas.

There are two ways to tell the “Patch” functionality where to apply different values

  • Zones: Splitting the mesh into zones (using named selections scoped to different but connected bodies)
  • Registers: Mark/Adapt “Region” (Creation of a cell register where the elements to be patched are “marked”)

The video shows the methodology, but also explains when you might want to use registers (When zones are not available)