A dynamic multi-grid block lattice Boltzmann method for three-dimensional moving boundary problems

A three-dimensional numerical framework of a shifting multi-grid block for moving boundaries based on multi-relaxation time lattice Boltzmann method is developed. This work is an extension of our previous two-dimensional algorithm [1] with significant improvements where low-order temporal interpolation has been replaced with a higher-order spatial interpolation scheme. The model has been validated for the cases i.e., sedimentation of a solid sphere in a fluid medium under the action of gravity. The results demonstrate that the moving multi-block improves the resolution of a geometry that reduces the fluctuations registered in velocity and force measurements for the single coarse mesh. This approach offers a substantial advantage in terms of a significant reduction in computational cost as the grid is refined only locally around the moving body as against a fully refined computational domain.