NUMERICAL CONSIDERATIONS IN SIMULATING A TURBULENT SUSPENSION OF FINITE-VOLUME PARTICLES

Direct numerical simulation of a dilute suspension of finite-volume sp heres requires computation of the time-varying fluid field and updatin g the particle momenta and positions, taking into account the effects due to particle-particle collisions. Collision calculations are inhere ntly an order N-p(2),operation, where N-p is the number of particles i n the system. Typical simulations contain 10(5)-10(6) particles making the brute force computation of collisions prohibitively expensive. An alternative algorithm, based on molecular-dynamic-simulation strategi es, 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 c oupling must be symmetric in order to ensure proper behavior of the ov erall energy balance. Asymmetric interpolation schemes will lead to er rors of one plus the error of the least accurate interpolation method per iteration. Of course, global errors may be much larger due to a cu mulative effect of the systematic deviation. (C) 1996 Academic Press, Inc.