Comparative study of momentum-exchange and smoothed profile methods in Lattice Boltzmann method

• The present work compares two methods for force evaluation in LBM.
• The simulation of flow past a sphere placed symmetrically in a cubic domain is done.
• Sedimentation of a spherical particle in a vertical channel is simulated.
• The smoothed profile method is more accurate than the momentum-exchange method.

Introduction: The present paper compares two methods for force evaluation in the Lattice Boltzmann method: the smoothed profile method (SPM) and momentum-exchange method.Methods: We carry out three-dimensional computations for stationary and moving curved boundaries including a spherical particle placed in the middle of a cubic domain, and sedimentation of a spherical particle in a vertical channel.Results and discussions: The smoothed profile method at small Reynolds numbers predicts accurate results but as the Reynolds number increases, deviation from the experimental results is observed. The momentum-exchange method is easier to implement, and predicts satisfactory results at all Reynolds numbers, but when the grid lacks resolution in the gap between the particle and domain boundaries or solid walls this method can no longer predict accurate hydrodynamic forces. At the region near the walls the smoothed profile method seems to be superior over the momentum-exchange method.