A novel incompressible finite-difference lattice Boltzmann equation for particle-laden flow

In this paper, we propose a novel incompressible finite-difference lattice Boltzmann Equation （FDLBE）. Because source terms that reflect the interaction between phases can be accurately described, the new model is suitable for simulating two-way coupling incompressible multiphase flow The 2-D particle-laden flow over a backward-facing step is chosen as a test case to validate the present method. Favorable results are obtained and the present scheme is shown to have good prospects in practical applications.

Linear Dynamical System over Finite Distributive Lattice

A finite dynamical system(FDS)over a lattice L is a pair(S(L),f),where S(L)is a left-L module and f is a mapping from S into itself.The phase space of(S(L),f)is a digraph whose vertex set is S(L)and there is an arc from x to y if y=f(x).Let L be a finite distributive lattice,A an n×n matrix over L,and f(x)=Ax.The structure of the phase space of the FDS(Ln,f)is discussed.The number of limit cycles in the phase space of(Ln,f)is described in Möbius function.The phase spaces of some invertible,nilpotent,and idempotent FDS(Ln,f)are characterized explicitly.

Size effect of lattice material and minimum weight design

The size effects of microstructure of lattice materials on structural analysis and minimum weight design are studied with extented multiscale finite element method（EMsFEM） in the paper. With the same volume of base material and configuration, the structural displacement and maximum axial stress of micro-rod of lattice structures with different sizes of microstructure are analyzed and compared.It is pointed out that different from the traditional mathematical homogenization method, EMsFEM is suitable for analyzing the structures which is constituted with lattice materials and composed of quantities of finite-sized micro-rods.The minimum weight design of structures composed of lattice material is studied with downscaling calculation of EMsFEM under stress constraints of micro-rods. The optimal design results show that the weight of the structure increases with the decrease of the size of basic sub-unit cells. The paper presents a new approach for analysis and optimization of lattice materials in complex engineering constructions.

EXTERNAL BODY FORCEIN FINITE DIFFERENCE LATTICE BOLTZMANN METHOD

A new finite difference lattice Boltzmann scheme is developed. Because of analyzing the influence of external body force roundly, the correct Navier-Stokes equations with the external body force are recovered, without any additional unphysical terms. And some numerical results are presented. The result which close agreement with analytical data shows the good performance of the model.

The Best Extending Cover-preserving Geometric Lattices of Semimodular Lattices

In 2010,Gábor Czédli and E.Tamás Schmidt mentioned that the best cover-preserving embedding of a given semimodular lattice is not known yet[A cover-preserving embedding of semimodular lattices into geometric lattices.Advances in Mathematics,225,2455-2463(2010)].That is to say:What are the geometric lattices G such that a given finite semimodular lattice L has a cover-preserving embedding into G with the smallest|G|?In this paper,we propose an algorithm to calculate all the best extending cover-preserving geometric lattices G of a given semimodular lattice L and prove that the length and the number of atoms of every best extending cover-preserving geometric lattice G equal the length of L and the number of non-zero join-irreducible elements of L,respectively.Therefore,we solve the problem on the best cover-preserving embedding of a given semimodular lattice raised by Gábor Czédli and E.Tamás Schmidt.

On Some Results in the Theory of Finite Partially Soluble Groups

This article provides an overview of some recent results and ideas relatedto the study of finite groups depending on the restrictions on some systems of theirsections.In particular,we discuss some properties of the lattice of all subgroups ofa finite group related with conditions of permutability and generalized subnormality for subgroups.The paper contains more than 30 open problems which were posed,atdifferent times,by some mathematicians working in the discussed direction.