Particle separation in flow

Warning

This tutorial is included in and relies on functionality that is available in the CFDEMcoupling-Premium package.

This tutorial models separation of different particles in (a very basic) separation unit of a combine harvester. Flow enters from the left and separates wheat grains from much lighter leaves with the leaves leaving through the flow exit and wheat grains falling to the bottom and leaving through the flow inlet – where we assume, for this setup, further sorting.

Note

This tutorial is located in CFDEMcoupling/useCases/harvester

Models used

• Fluid solver: cfdemSolverPimple

• DEMbasedDrag models the momentum coupling between particles and fluid by calculating the drag force on the DEM side. In this tutorial the Zastawny drag model is used.

• Impact of chaffer motion on the flow is modelled by an immersed boundary method (IBM) implemented in IBMeshMotion. The actual contact detection between particles and wall is handled on the DEM side where mesh motion is implemented using a mesh_module motion with the identical settings.

Wheat and leaf particles are described as prolate ellipsoids with the leaf particles having a higher aspect ratio. On the CFD side, both particle types are approximated as spheres with equivalent volume. All computational effort involving the exact particle shape and orientation, including the computation of drag forces, is done on the DEM side where this information is readily available.

Results

Figure 1: Fluid velocity magnitude and the particles at the end of the simulation. Wheat grain particles are shown in gold / yellow and leaf particles in dark green.