Luuk Seelen

An efficient multi-particle collision approach to large-scale dissipative granular flow

Introduction

  • A large fraction of bulk materials, including food, fuel and other products, are produced in fluidized bed reactors.
  • Challenges in improving these reactors include the dissipative nature of the particle collisions, and the non-linear drag.
  • These effects lead to large scale heterogeneity and clusters of particles.
  • State of the art DPM models are limited to up to 105 particles, making the prediction of the large scale structures impossible.
  • Continuum models have the difficulty of good closures for the solid phase.
  • Recent advances in soft matter physics have given new coarse-grained multi-particle collision algorithms

Objective

  • To adapt the multi-particle collision dynamics method to the macroscopic granular flow scale and couple it with a CFD gas flow solver.
  • To simulate tens of millions of granular particles to study the role of dissipation in the formation of large-scale heterogeneities.

Modeling approach

  • The multi-particle collision dynamics (MPCD) algorithm defines collisions between clouds of neighboring particles.
  • These cell pairs exchange momentum in 3 ways in 2D. Horizontal (σ1), vertical (σ2) and diagonally along σ3 and σ4.
  • To maintain isotropy the probabilities w and wd should be chosen correctly.
  • By biasing the probability of performing a collision, a non-ideal equation of state is created, with a free parameter to tune the equation of state.

Outlook

  • Build a 3D version of the MPCD method, and check the isotropy of the method.
  • Derive the equation of state for the 3D MPCD method.
  • By changing the collision acceptance probability, tune the equation of state to that of a hard-sphere gas.

Acknowledgement

  • This work is part of the European Research Council (ERC) Advanced Grant.

References

  1. Andrews, A.T. IV. and Sundaresan, S., 2005. Closures for filtered two-fluid model equations of gas-particle flows.
  2. Ihle, T., Tüzel, E. and Kroll, D.M., Consistent particle-based algorithm with a non-ideal equation of state, Europhys. Lett. 73, 664 (2006)