Project Title:

Tumbling of a Rigid Elliptical Particle in Confined Simple Shear Flow using Overset Meshing in OpenFOAM v2312.


Description:

This case simulates the rotational motion (Jeffery orbit) of a rigid elliptical particle suspended in a confined simple shear flow using the overPimpleDyMFoam solver available in OpenFOAM v2312.

The simulation employs a two-component overset mesh consisting of:
1. Stationary background mesh
2. Moving body-fitted overset mesh surrounding the ellipse

Rigid body motion is solved using the sixDoFRigidBodyMotion library. The motion of the ellipse is driven solely by hydrodynamic forces and moments due to the shear flow.


Case Specifications:

Solver              : overPimpleDyMFoam
OpenFOAM Version    : v2312

Flow Type           : Laminar
Reynolds Number     : 0.01
Shear Rate          : 0.01 s^-1

Particle Shape      : Ellipse
Semi-major axis (a) : 1.0
Semi-minor axis (b) : 0.5

Initial Orientation : 15°

Motion              : Free Rotation Due to Shear Flow
Gravity             : Disabled


Mesh:

Mesh Type		: Two-component overset mesh
Component 1		: Background structured mesh
Component 2		: Body-fitted mesh surrounding the ellipse
Interpolation Method	: cellVolumeWeights


Directory Structure of cylinderAndBackground:

0.orig/
    Initial and boundary conditions

constant/
    polyMesh/
    dynamicMeshDict
    transportProperties

system/
    blockMeshDict
    controlDict
    createPatchDict
    fvSchemes
    fvSolution
    topoSetDict
    setFieldsDict
    setExprFieldsDict
    decomposeParDict

Allrun
Allclean


Running the Case:

1. Source OpenFOAM
   source /usr/lib/openfoam/openfoam2312/etc/bashrc

2. Clean previous results
   ./Allclean

3. Run the complete case
   ./Allrun


Post-Processing: 

The following quantities are monitored:

- Angular velocity
- Orientation tensor
- Centre of mass
- Hydrodynamic forces
- Hydrodynamic moments

The simulation results can be visualized using: ParaView


Validation:

The numerical angular velocity is compared with the analytical Jeffery solution for an elliptical particle in simple shear flow.
The comparison is performed using the dimensionless angular velocity:

    ω / γ̇

against

    γ̇ t


Important Points:

• The case is configured for OpenFOAM v2312.

• The overset interpolation method is set to leastSquares to improve interpolation accuracy and reduce numerical diffusion but was changed to cellVolumeWeights.

• The rigid body is initially oriented at 15° with respect to the flow direction.

• Gravity is disabled to simulate pure shear-driven tumbling.

• This case assumes laminar incompressible flow.

