Numerical Considerations in Simulating a Turbulent Suspension of Finite-Volume Particles

Direct numerical simulation of a dilute suspension offinite-volumespheres requires computation of the time-varying fluid field and updating the particle momenta and positions, taking into account the effects due to particle?particle collisions. Collision calculations are inherently an orderN2poperation, whereNpis the number of particles in the system. Typical simulations contain 105?106particles making the brute force computation of collisions prohibitively expensive. An alternative algorithm, based on molecular-dynamic-simulation strategies, is proposed in this paper. A second consideration in simulating a finite-volume particle suspension is how the particle forces should be coupled back into the fluid calculation (so-called reverse coupling). Careful consideration of the energy budget for the particle and fluid phases indicates that interpolation schemes for forward and reverse coupling must be symmetric in order to ensure proper behavior of the overall energy balance. Asymmetric interpolation schemes will lead to errors of one plus the error of the least accurate interpolation method per iteration. Of course, global errors may be much larger due to a cumulative effect of the systematic deviation.