Li Xuhui

Harbin Engineering University · Department of Naval Architecture & Ocean Engineering

In the present work, the force term is first derived in the spectral multiple-relaxation-time high-order lattice Boltzmann model. The force term in the Boltzmann equation is expanded in the Hermite temperature rescaled central moment space (RCM), instead of the Hermite raw moment space (RM). The contribution of nonequilibrium RCM moments beyond sec...

We present an a priori derivation of the force scheme for lattice Boltzmann method based on kinetic theoretical formulation. We show that the discrete lattice effect, previously eliminated a posteriori in BGK collision model, is due to first-order space-time discretization and can be eliminated generically for a wide range of collision models with...

Water entry is one of the important topics in ship and offshore structures. Among the structures, water entry of bow-flare section with bulbous bow could be one of the most difficult problems due to its complex geometry. To investigate the problem, a numerical model which can simulate water entry of complex objects is developed in this paper. In th...

Ship bow waves are quite common during ship navigation. A thorough investigation of the bow waves will contribute to a better understanding of the formation process of wave pattern as well as its wave-forming resistance. At present, computational cost of direct simulation of ship bow waves using three-dimensional Computational Fluid Dynamics (CFD)...

Numerical stability issue has always been the bottleneck that plagues the wide application of lattice Boltzmann methods in the flow scenarios of high Reynolds number and high Mach number. To improve the numerical stability and accuracy of the collision models in the field of lattice Boltzmann methods has been a research hotspot and difficulty in th...

The Bhatnagar–Gross–Krook (BGK) single-relaxation-time collision model for the Boltzmann equation serves as the foundation of the lattice BGK (LBGK) method developed in recent years. The description of the collision as a uniform relaxation process of the distribution function towards its equilibrium is, in many scenarios, simplistic. Based on a pre...

Modified surfaces with rough structure have been widely employed to enhance the critical heat flux (CHF) in the heat transfer engineering. Since any structure diagram in its intersecting surface can be treated as spectrum/ signal in 2D dimensions, and any spectrum in time domain and in frequency domain can be transformed into sine transforms by the...

We point out that the minimal components of the tensorial moments of the distribution that can be independently relaxed in collision without violating rotational symmetry are its irreducible representation (irrep) of SO(3), and a generic multiple-relaxation-time collision model can be constructed by independently relaxing these components. As the s...

The Bhatnagar-Gross-Krook (BGK) single-relaxation-time collision model for the Boltzmann equation serves as the foundation of the lattice BGK (LBGK) method developed in recent years. The description of the collision as a uniform relaxation process of the distribution function towards its equilibrium is, in many scenarios, simplistic. Based on a pre...

In this paper, a lattice Boltzmann (LB) scheme for simulating free-surface flows is investigated, in which the Hermite expansion-based regularization (Zhang et al., 2006) and the single-phase free-surface model (Körner et al., 2005) are adopted. It is pointed out that the original free-surface model may encounter some conflicting situations when de...

In the Hermite-expansion-based multiple-relaxation-time lattice Boltzmann (LB) model [Shan & Chen, Int. J. Mod. Phys. C, 18, 635, (2007)], a separate relaxation time is assigned to each of the tensorial moments of the collision term. Here we point out that to allow maximum flexibility while preserving the rotational symmetry of the relaxation physi...

Enhancing Critical Heat Flux (CHF) in pool boiling significantly extends the safety limit in the nuclear system, especially under the In-Vessel Retention-Reactor Vessel Cooling (IVR-ERVC) severe accident management strategy to avoid the failure of the lower head reactor pressure vessel. In this work, the lattice Boltzmann method (LBM) is employed t...

We postulate that the relaxations of the distribution function in the lattice Boltzmann model should be self-similar under temperature scaling. Based on this postulation, a multiple-relaxation-time collision model in the relative, temperature-scaled reference frame is devised with Hermite expansion. Resorting to the relation between the Hermite bas...

In the work of N. Martys et al. [Nicos S. Martys, Xiaowen Shan, Hudong Chen, Phys. Rev. E, Vol. 58, Num.5, 1998 ], a self-consistent force term to any order in the Boltzmann-BKG equation is derived by the Hermite basis with raw velocity. As an extension, in the present work, the force term is expanded by the Hermite basis with the relative velocity...

In the present study, we have developed the free surface LBM (FSLBM) algorithm for wave-structure interaction flow problem. Standard Single Relaxation Time (SRT) approximation with the Bhatnagar-Gross-Krook (BGK) collision model were used. In addition, a Smagorinsky Large Eddie Simulation (LES) Model was implemented in order to capture turbulent st...