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1 MRFSimpleFoam Tutorial

1.1 Introduction

This tutorial is aimed to generating the mesh in Gambit, importing and solving it with MRFSimpleFoam. It applies to Valid versions: OF version 141.png

1.2 Mesh Generation and Import

  1. generate two cylinders (r1=0.5 h1=1; r2=0.25, h2=0.5) and one cube (h3=0.3)
    Domain generation
  2. subtract cylinder 2 from 1 (maintain cylinder 2)
  3. subtract cube 3 from cylinder 2
  4. Connect the faces (inner face of cylinder 1 and outer face of cylinder 2)
    Connect faces
  5. define continuum types (zones): rotor for cylinder 2, and stator for cylinder 1
    Rotor/Stator domain
  6. define boundaries (inlet, outlet, cubeWall, cylindricWall, sliderFace).sliderFace is the connected faces mentioned above.
  7. define the boundary for sliderFace as INTERIOR
  8. generate tetrahedral mesh (0.05 size)

NOTE: It is advisable not to make any modifications to the topology after meshing.

  1. export as mrf.msh
  2. import mesh in OpenFoam:
 fluentMeshToFoam ./ simulation geom/mrf.msh -writeSets -writeZones

1.3 Solver Running

Before you start the solver, another modification is needed: change in all the dictionaries the patch cubeWall with rotor and cylindricWall with stator. Of course you could name this patches as it should from the beginning in Gambit, but I considered that in this way it will be clearer since the same name rotor appears in two places: zone and patch.

The rotational axis, and the angular velocity are specified using a dictionary file named constant/MRFZones.

The solver can be started as:

MRFSimpleFoam ./ simulation

It is advisable to start with very low angular velocities, even better to use potentialFoam as an initialization step. potentialFoam runs directly on the case withouth any other modifications.

In the case I ran, I started with potentialFoam, then I increased gradually the angular velocity from 0, 10, 20, 50, to 100 rad/s.

1.4 Postprocessing

Pressure distribution in a middle cross section is shown in the next figure:
Pressure distribution

1.5 Download

The complete case and solver: [[1]]

NOTE: To run this case in OF1.6 include the file constant/RASproperties