Particle-resolved DNS of turbulent channel flow with a fixed array of particles

For particles larger than the Kolmogorov scale point-particle DNS becomes inaccurate due to the use of correlations for the drag force which only hold if particles are small compared to the Kolmogorov scale. A way to improve these correlations is by particle-resolved DNS. We developed an overset grid method for particle-laden channel flow. In this method a global rectangular grid is used for the complete domain and each particle has its own spherical grid. Especially in case of dilute flows the computational effort is far less than in the immersed boundary method, since the global rectangular grid does not need to resolve the flow around a particle.
We used this method for turbulent flow in a channel with an array of particles that move with constant velocity with respect to the wall and used this to calculate the force on a particle and its dependence on the fluid velocity field around the particle. In this way we determined optimal values for the coefficients in the Schiller-Naumann correlation for the drag force. The use of this optimal correlation in point-particle DNS results in better agreement with the results for the particle-resolved simulation than the standard Chiller-Naumann correlation.

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