Large-scale DNS of gas–solid flows on Mole-8.5

Direct numerical simulation (DNS) for gas–solid flow is implemented on a multi-scale supercomputing system—Mole-8.5 featuring massive parallel GPU–CPU hybrid computing, for which the lattice Boltzmann method (LBM) is deployed together with the immersed moving boundary (IMB) method and discrete element method (DEM). Numerical schemes and their GPU parallelism strategy are described in detail, where more than 40-fold speedup is achieved on one Nvidia C2050 GPU over one core of Intel E5520 CPU in double precision, and nearly ideal scalability is maintained when using up to 672 GPUs. A two-dimensional suspension with 1,166,400 75-μm solid particles distributed in an area of 11.5 cm×46 cm, and a three-dimensional suspension with 129,024 solid particles in a domain of 0.384 cm×1.512 cm×0.384 cm are fully resolved below particle scale and distinct multi-scale heterogeneity are observed. The simulations demonstrate that LBM–IMB–DEM modeling with parallel GPU computing may suggest a promising approach for exploring the fundamental mechanisms and constitutive laws of complex gas–solid flow, which are, so far, poorly understood in both experiments and theoretical studies.

► Direct numerical simulation of gas–solid flow is implemented by coupling GPU and CPU.
► LBM is deployed with immersed moving boundary and DEM in this implementation.
► More than 40-fold speedup is achieved on each Fermi GPU compared with one CPU core.
► Both large-scale 2D and 3D suspensions are fully resolved below particle scale.