Mechanical load on a particle aggregate in mono-axial elongational flow

Abstract

Subject of the present contribution is the numerical simulation of the effect of a elongational flow field on a suspended particle-aggregate. The particle-aggregate consists of seven rigid spherical particles and is suspended in the flow field at low Re-numbers (Re=0.01–0.1). The ratio of particle and fluid densities varies between 1 and 15. The velocity and pressure distribution is obtained from the numerical solution of the Navier–Stokes equation and the continuity equation based on finite volume methods. The particle motion is obtained from the Euler equation of motion for rigid bodies. A comparison of classical solutions with the result of the numerical simulation for a spherical particle shows a very good agreement. It can be shown, that the interaction of the aggregate with the fluid differs clearly from that of a spherical particle. Furthermore, it has been found that the magnitude of stresses on the aggregate surface is increasing with time monotonously. Shear stress is maximum on the outer parts of the aggregate. Normal stress takes on maximum values on the upstream and downstream oriented faces. The maximum pressure drop across the particle results in an extensional force which increases in time within the considered period.