Settling of a single particle vs. analytic solution

In this test case a single particle is released in a container and settles due to gravity. The evolution of particle velocity is benchmarked against the analytical Stokes solution for low Reynolds numbers.

Note

This case is located in CFDEMcoupling/validationCases/settlingTest_analytic.

The particular simulation discussed in this article is run with cfdemSolverPiso, a spherical particle, and the SchillerNaumann drag model.

There are numerous variations of the this settling case for different solvers, model combinations, and particle shapes in the tutorials directory.

Models used

• Particle forces:

  • The drag force is computed by the SchillerNaumann drag model.

  • Alteration of effective gravity forces due to the difference of fluid and particle densities is modelled by the Archimedes force model.

• Particles are mapped to CFD by the engine locateModel.

• The voidfraction is computed by the divided voidfraction model.

• Momentum exchange between particles and fluid is computed in an implicit manner, see Zhou et al. (2010), JFM.

Results

Figure 1: Evolution of particle settling velocity over time. The analytic solution is a squired by an independent implementation of the Schiller Naumann correlation for the drag coefficient and manual integration of the particle velocity from the equilibrium of gravitational and drag force.