(142af) Effect of Inertia On Particle Trajectories Around a Spherical Obstacle

We investigate inertia effects on the motion of a spherical particle past a fixed spherical obstacle of the same radius under the action of a constant force in a quiescent ambient fluid, using lattice Boltzmann simulations. The obstacle is located at the origin of coordinates, while the particle starts its motion far upstream to the obstacle along x-axis with an initial offset y^-∞ = b_in. We use the distance of closet approach of the particle from the obstacle  and the far downstream offset y^∞ = b_out above x-axis, as functions of the initial offset, as indicator variables to probe inertia effects on the trajectories. The computational method allows us to isolate and study the individual effects of particle and fluid inertia, quantified by Stokes and Reynolds numbers, respectively. We observe that, (a) as expected the particle trajectories are asymmetric, (b) the particle attains a smaller distance of closest approach from the obstacle due tothe presence of particle and/or fluid inertia, (c) the far downstream offset b_out is smaller than the far upstream one b_in when particle inertia is significant. Fluid inertia alone, on the other hand, does not significantly affect the behaviour of the far downstream offset for Re<2.5.