Fluent-v6111movingzones.ppt

Moving Zones Introduction Many engineering problems involve flows through domains which contain translating or rotating components Examples – Translational motion: Train moving in a tunnel, longitudinal sloshing of fluid in a tank, etc. Examples – Rotational motion: Flow though propellers, axial turbine blades, radial pump impellers, etc. Fluent provides four modeling approaches for moving zone models: Single Reference Frame Model SRF Multiple Reference Frame Model MRF Mixing Plane Model MPM Sliding Mesh Model SMM Basic implementation assumes motions are steady i.e. constant linear velocity or rotational speed accelerating reference frames can be modeled with source terms not considered here Overview of Modeling Approaches Single Reference Frame SRF Entire computational domain is referred to a moving reference frame Multiple Reference Frame MRF Selected regions of the domain are referred to moving reference frames Interaction effects are ignored ? steady-state Mixing Plane MPM Influence of neighboring regions accounted for through use of a mixing plane model at rotating/stationary domain interfaces Circumferential non-uniformities in the flow are ignored ? steady-state Sliding Mesh SMM Motion of specific regions accounted for by a mesh motion algorithm Flow variables interpolated across a sliding interface Unsteady problem - can capture all interaction effects with complete fidelity, but more computationally expensive than SRF, MRF, or MPM NOTE: With the exception of sliding mesh problems, constant translational motion is generally not of interest since there are no accelerations acting upon the fluid. Therefore, for SRF, MRF, and MPM, we will focus exclusively on rotational problems Introduction to SRF Modeling SRF assumes a single fluid domain which rotates with a constant speed with respect to a specified axis. Why use a rotating reference frame? Flow field which is unsteady when referred to a stationary frame becomes steady in the rota