Overset grids and moving bodies
Choose how a grid represents relative motion, from blades to flap deployment.
Overset (Chimera)
Build overlapping component grids and a background grid. Hole cutting deactivates cells inside solid bodies or otherwise covered regions. The solver identifies donor cells and interpolates data to receptor points. This is useful when components move independently or are easier to mesh separately.
Check that overlap and donor coverage remain adequate throughout motion. Similar resolution across an interface can help carry wakes. Interpolation can affect conservation and accuracy, depending on the coupling formulation. Avoid letting orphan points or heavily stretched donor cells go unnoticed.
Sliding interfaces and rotating frames
A sliding interface couples separate mesh zones across an interface as one moves relative to the other. It can capture blade passage and time-dependent rotor–airframe interactions. A steady multiple-reference-frame (MRF) approximation can be a cheaper baseline for mean behavior when the frozen relative position is acceptable. Mesh deformation or remeshing is another option for motion that changes the fluid domain.
An actuator disk can model prescribed rotor loading without resolving individual blades. That is a modeling choice and still requires wake resolution.