While continuous rotation of solid objects such as a wind turbine is modeled by sliding mesh in Polaris CFD, numerous other applications involve fluid flow and moving geometries. Valve open/closure, piston's reciprocating movement, wing flapping, to name a few, all fall into this category in which the motion of rigid body is partially constrained.
Unconstrained six degrees of freedom (6-DOF) rigid body motion under aerodynamics and external loads is a challenging physical problem. Countless important applications exist, including store separation from an aircraft, booster separation from the main space vehicle, projectile and simulation of flight control.
Polaris CFD provides simulation capability of true moving geometry. By taking advantage of its efficient inline discretization and generalized Gas kinetic boundary conditions, it becomes feasible to accurately simulate moving solids without excessive simulation performance penalty in Polaris. In near future, sliding mesh capability for rotating geometries will be available too.
Polaris CFD solver applies flow induced forces and torques to solid objects and integrates the Newton-Euler equations for 6-DOF rigid body motion, or pre-defined motion. The position and momentum of solid objects are fed back into the CFD solver, which usually calls for a partial rediscretization. All work is performed inside one solver seamlessly. The complex physical phenomenon is modeled by a few mouse clicks.