An efficient algorithm for the calculation of sub-grid distances for higher-order LBM boundary conditions in a GPU simulation environment

This paper presents a new and efficient algorithm for the calculation of sub-grid distances in the context of a lattice Boltzmann method (LBM). LBMs usually operate on equidistant Cartesian grids and represent moving geometries by either using immersed boundary conditions or dynamic fill algorithms in combination with slip or no-slip boundary conditions. In order to obtain sufficiently high geometric accuracy, the sub-grid distances from Eulerian fluid nodes on uniform and structured grids to a tessellated triangular surface mesh have to be calculated. The proposed algorithm extends a previously published grid generation procedure by an efficient calculation of sub-grid distances. The algorithm is optimized for massively parallel execution on graphics processing units (GPUs). Based on a linearized representation of the obstacle surface, surface normal vectors are computed and stored, which then serve to compute the sub-grid distances. This saves GPU memory, re-uses information that is available from the surface voxelization step, and has shown to be very accurate and efficient for the implementation in a state-of-the-art LBM-GPU solver.

Subjects

Graphics processing unit (GPU)

Grid generation

LBM

Linear-interpolated bounce-back

Sub-grid distances

Funding(s)

Einfluss der Formgebung von Schiffen auf die Propulsionseffizienz und Propeller-Eis-Belastung; Modellierung der Umströmung von Schiffen in eisbedeckten Gewässern

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An efficient algorithm for the calculation of sub-grid distances for higher-order LBM boundary conditions in a GPU simulation environment