Towards simulation of clogging effects in wastewater pumps: Modelling of Fluid Forces on a Fiber of Bonded Particles using a Coupled CFD-DEM Approach

Clogging in wastewater pumps is often caused by textile and other fibrous materials in the wastewater. As a step towards developing a methodology using the CFD-DEM approach for simulation of clogging effects, a fiber model consisting of a string of bonded DEM particles is developed in the software EDEM and coupled (two-way momentum exchange) to the CFD software ANSYS Fluent. The number of particle segments forming the fiber as well as the properties of fiber density and fiber stiffness are changed to identify the influnce of these properties on the fiber motion in shear flow. A change of density from 500 kg/m³ to 5000 kg/m³ strongly affects the motion of the fiber, while a change of the stiffness of the bonds between the spherical particles from 1e⁷ to 1e⁹ has less influence on the fiber motion. The results of using 20 and 50 fiber segments respectively are similar in the first period of simulation, but the deviation between the two cases increase with time. The difference may be caused by the difference in fiber aspect ratio in the two cases. The influence of fiber properties on fiber motion has been analysed quantitatively and compared to fiber orbit types presented in literature [8],[11]. The results show that fiber motion similar to the motion presented in literature is obtained using a coupling between EDEM and ANSYS Fluent.