Correction scheme for point-particle two-way coupling applied to nonlinear drag law

TL;DR

This paper extends a correction scheme for estimating undisturbed fluid velocity in two-way coupled point-particle simulations to finite Reynolds numbers, improving accuracy in predicting particle behavior.

Contribution

It adapts and tests the correction scheme for particles at finite Reynolds numbers using the Schiller-Nauman drag law, demonstrating significant error reduction.

Findings

Achieves over 70% reduction in velocity errors.

Accurately predicts settling velocities up to Reynolds number 10.

Provides a regime diagram for correction scheme selection.

Abstract

Drag laws for particles in fluids are often expressed in terms of the undisturbed fluid velocity, defined as the fluid velocity a particle sees before the disturbance develops in the fluid. In two-way coupled point-particle simulations the information from the undisturbed state is not available and must be approximated using the disturbed velocity field. Horwitz and Mani (2016) recently developed a procedure to estimate the undisturbed velocity for particles moving at low Reynolds number and obeying the Stokes drag law. Using our correction, we demonstrated convergence of numerical simulations to expected physical behavior for a range of canonical settings. In this paper we further extend and examine that correction scheme for particles moving at finite Reynolds number, by considering the Schiller-Nauman drag law. Tests of particle settling in an otherwise quiescent fluid show reasonable predictions of settling velocity history for particle Reynolds numbers up to ten. The correction scheme is shown to lead to $\geq 70\%$ reduction in particle velocity errors, compared to standard trilinear interpolation of disturbed velocities. We also discuss the modelling of unsteady effects and their relation to Stokes number and density ratio. Finally, we propose a regime diagram to guide scheme selection for point-particle modelling.