## 1.4. Immersed Solids

The Immersed Solids capability of CFX enables you to model steady-state or transient simulations involving rigid solid objects that can move through fluid domains. The model involves the use of an immersed solid domain that is placed inside a fluid domain to represent the rigid solid object, including its shape, position, orientation, and velocity. As a simulation proceeds, CFX-Solver calculates which parts of the fluid domain are overlapped by the immersed solid (that is, are within the immersed solid domain), and applies a source of momentum to the fluid inside the immersed solid domain in order to force the flow to move with the solid. This has the effect of making the flow outside of the immersed solid domain behave as if it were flowing around a rigid solid object. Additional forcing terms are applied at the boundary in order to improve the near-wall behavior of the flow near the immersed solid boundary.

The following topics are discussed:

- Momentum Sources
- Near-Wall Treatment for Immersed Solid Boundary

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