ROCKY DEM- CFD simulation for Realistic Granular Flow in an Aerodynamic separating device.

Abstract. In this investigation, a computational study of the air–granular flow in an aerodynamic harvesting and separation machine is investigated using the realistic dimensions and shape of the particles. This was done by the integration of the Discrete Element Method (DEM-Rocky 4.13) and Computational Fluid Dynamics (CFD-ANSYS Fluent 18.0) software using the one-way coupling approach. The machine was designed and constructed using cyclonic separation approach to harvest jojoba seeds from the soil surface. During that, a lot of undesired materials such as leaves, stones, and sand, etc. were sucked and introduced with seeds to the inlet of the cyclone. The behavior of this real granular flow phase inside the reverse-flow centrifugal separator is captured by DEM model using Newton‘s equations of motion to every individual particle where the continuum airflow is modeled by CFD which uses Navier–Stokes equations at a computational cell scale. The simulation was only carried out on two groups of particles; jojoba seeds and its leaves. The main objective in this investigation is to study the effect of leaves mass loading to seeds ratios which can be regarded as 10, 20, 30, 40, and 50% on the separation efficiency at a fixed inlet air velocity of 30 ms-1. During the simulation, the particle-particle and the particle-boundary interaction forces were taken into consideration. The current simulations successfully capture a good prediction of the separation efficiency at the designed conditions according to particles real-shape, which showed a good match between the experimental result and computational data. It is concluded that, when using the designed cyclone separator geometry for harvesting jojoba seeds, it will give a reasonable separation of seeds from the undesired materials.