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Abstract
The
intricate motions and complex vortical structures generated by the
interaction between fluids and solids are visually fascinating. However,
reproducing such a two-way coupling between thin objects and turbulent
fluids numerically is notoriously challenging and computationally
costly: existing approaches such as cut-cell or immersed-boundary
methods have difficulty achieving physical accuracy, or even visual
plausibility, of simulations involving fast-evolving flows with immersed
objects of arbitrary shapes. In this paper, we propose an efficient and
versatile approach for simulating two-way fluid-solid coupling within
the kinetic (lattice-Boltzmann) fluid simulation framework, valid for
both laminar and highly turbulent flows, and for both thick and thin
objects. We introduce a novel hybrid approach to fluid-solid coupling
which systematically involves a mesoscopic double-sided bounce-back
scheme followed by a cut-cell velocity correction for a more robust and
plausible treatment of turbulent flows near moving (thin) solids,
preventing flow penetration and reducing boundary artifacts
significantly. Coupled with an efficient approximation to simplify
geometric computations, the whole boundary treatment method preserves
the inherent massively parallel computational nature of the kinetic
method. Moreover, we propose simple GPU optimizations of the core LBM
algorithm which achieve an even higher computational efficiency than the
state-of-the-art kinetic fluid solvers in graphics. We demonstrate the
accuracy and efficacy of our two-way coupling through various
challenging simulations involving a variety of rigid body solids and
fluids at both high and low Reynolds numbers. Finally, comparisons to
existing methods on benchmark data and real experiments further
highlight the superiority of our method.
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