For many flow problems involving one or more rotating parts (such as impellers, pumps, fans, etc.,), setting up the flow simulation in a single stationary reference frame is complicated. In such cases, one of the approaches is to introduce multiple rotating frames (MRF) to simply the simulation. This approach idealizes the flow around the moving parts as steady-state and eliminates the need for expensive transient simulations with moving meshes.
In the current workflow, the flow around a turbine section is simulated by creating an MRF zone around it. By assigning the angular velocity and the axis of rotation to the MRF zone, the flow problem is analogous to freezing the motion of the turbine and observing the instantaneous flow field within the MRF zone; thus a "frozen rotor approach.".
Some of the basic requirements to set up an MRF flow simulation is also discussed here. A preliminary requirement is that the flow field at the MRF interface be steady. Further, another important requirement is that the stationary walls of the MRF geometries inside the MRF zone, fluid-fluid interfaces around MRF zone must be axisymmetric. The effect of the simplification is that the relative motion between the adjacent reference frames is not accounted for. Many more important settings, requirements, assumptions and considerations are discussed that can help model, solve and analyze the MRF flow simulations accurately.
With the high performance modeling, meshing, computing and visualization capabilities of the 3DEXPERIENCE platform, this workflow enables the fluid engineers to solve super large-scale fluid problems involving hundreds of millions of degrees of freedom. These unique capabilities provide high fidelity results and confidence for the detailed analysis. This Best Practice document is for Fluid Dynamics Engineers in the Transportation & Mobility (T&M), Aerospace & Defense (A&D), and Industrial Equipment (IE) industries.
Target audience: This Best Practices document is for Fluid Dynamics Engineers in the Transportation and Mobility (T&M), Aerospace & Defense (A&D), and Industrial Equipment (IE) industries.
In this Best Practice, you will learn about:
- Creating a fluid domain
- Generating hex-dominant mesh with appropriate specifications
- Creating a steady-state step with appropriate physics behavior
- Assigning the boundary conditions
- Creating the MRF Zone with appropriate wall conditions and rotational velocity
- Performing pre-simulation checks
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