A cost-effective search of collision pairs in Lagrangian particle tracking method

In the simulation of particle-laden flows, in which the interparticle collisions have to be considered, using the Eulerian- Lagrangian approach, it is agreed that the search of collision pairs based on the deterministic particle tracking method together with the binary-collision, hard-sphere model is a time consuming job in the computational procedure particularly for the flow laden with a remarkably high number density of particles. A cost-effective algorithm for the particle tracking processes which include solving the equations of motion, searching the collision pairs, and updating the list of neighboring particles' indices is developed. It is demonstrated in the turbulent, fully developed, particle-laden channel flows that the computational expenditure required for completing the particle tracking processes in a given Lagrangian time step can be optimally made with an approximately linear proportionally to the total number of particles ( N_PT ) by setting the number of Lagrangian cells ( N_cell ) for computation in accordance with the criterion of N_PT / N_cell = O (10⁰).