A numerical study for WENO scheme-based on different lattice Boltzmann flux solver for compressible flows

In this paper,the finite difference weighted essentially non-oscillatory (WENO) scheme is incorporated into the recently developed four kinds of lattice Boltzmann flux solver (LBFS) to simulate compressible flows,including inviscid LBFS Ⅰ,viscous LBFS Ⅱ,hybrid LBFS Ⅲ and hybrid LBFS Ⅳ.Hybrid LBFS can automatically realize the switch between inviscid LBFS Ⅰ and viscous LBFS Ⅱ through introducing a switch function.The resultant hybrid WENO-LBFS scheme absorbs the advantages of WENO scheme and hybrid LBFS.We investigate the performance of WENO scheme based on four kinds of LBFS systematically.Numerical results indicate that the devopled hybrid WENO-LBFS scheme has high accuracy,high resolution and no oscillations.It can not only accurately calculate smooth solutions,but also can effectively capture contact discontinuities and strong shock waves.

Distribution and chemical speciation of arsenic in different sized atmospheric particulate matters

The distribution and chemical speciation of arsenic(As)in different sized atmospheric particulate matters(PMs),including total suspended particles(TSP),PM_(10),and PM_(2.5),collected from Baoding,China were analyzed.The average total mass concentrations of As in TSP,PM_(10),and PM_(2.5)were 31.5,35.3,and 54.1μg/g,respectively,with an order of PM_(2.5)>PM_(10)>TSP,revealing that As is prone to accumulate on fine particles.Due to the divergent toxicities of different As species,speciation analysis of As in PMs is further conducted.Most of previous studies mainly focused on inorganic arsenite(iAs^(Ⅲ)),inorganic arsenate(iAs^(Ⅴ)),monomethylarsonate(MMA),and dimethylarsinate(DMA)in PMs,while the identification and sensitive quantification of trimethylarsine oxide(TMAO)were rarely reported.In this study,a high-performance liquid chromatography coupled to inductively coupled plasma mass spectrometry system was optimized for As speciation including TMAO in PMs.An anion exchange column was used to separate MMA,DMA and iAs^(Ⅴ),while a cation exchange column to separate TMAO and iAs^(Ⅲ).Results showed that iAs^(Ⅴ) was the dominate component in all the samples,corresponding to a portion of 79.2%±9.3%of the total extractable species,while iAs^(Ⅲ),TMAO and DMA made up the remaining 21%.Our study demonstrated that iAs^(Ⅲ) accounted for about 14.4%±11.4%of the total extracted species,with an average concentration of 1.7±1.6 ng/m^(3).It is worth noting that TMAO was widely present in the samples(84 out of 97 samples),which supported the assumption that TMAO was ubiquitous in atmospheric particles.

Numerical Investigation of"Frog-Leap"Mechanisms of Three Particles Aligned Moving in an Inclined Channel Flow

Intrigued by our recent experimental work(H.Yamaguchi and X.D.Ni-u,J.Fluids Eng.,133(2011),041302),the present study numerically investigate theflow-structure interactions(FSI)of three rigid circular particles aligned moving in an inclined channelflow at intermediate Reynolds numbers by using a momentum-exchanged immersed boundary-lattice Boltzmann method.A"frog-leap"phenomenon observed in the experiment is successfully captured by the present simulation and flow characteristics and underlying FSI mechanisms of it are explored by examining the ef-fects of the channel inclined angles and Reynolds numbers.It is found that the asym-metric difference of the vorticity distributions on the particle surface is the main cause of the"frog-leap"when particle moves in the boundary layer near the lower channel boundary.

A Numerical Study of Jet Propulsion of an Oblate Jellyfish Using a Momentum Exchange-Based Immersed Boundary-Lattice Boltzmann Method

In present paper,the locomotion of an oblate jellyfish is numerically investigated by using a momentum exchange-based immersed boundary-Lattice Boltzmann method based on a dynamic model describing the oblate jellyfish.The present investigation is agreed fairly well with the previous experimental works.The Reynolds number and the mass density of the jellyfish are found to have significant effects on the locomotion of the oblate jellyfish.Increasing Reynolds number,the motion frequency of the jellyfish becomes slow due to the reduced work done for the pulsations,and decreases and increases before and after the mass density ratio of the jellyfish to the carried fluid is 0.1.The total work increases rapidly at small mass density ratios and slowly increases to a constant value at large mass density ratio.Moreover,as mass density ratio increases,the maximum forward velocity significantly reduces in the contraction stage,while the minimum forward velocity increases in the relaxation stage.

UnsteadyMHD Non-Darcian Flow Over a Vertical Stretching Plate Embedded in a Porous Medium with Thermal Non-EquilibriumModel

An analysis is performed to study the influence of local thermal nonequilibrium(LTNE)on unsteadyMHDlaminar boundary layer flowof viscous,incompressible fluid over a vertical stretching plate embedded in a sparsely packed porous medium in the presence of heat generation/absorption.The flow in the porous medium is governed by Brinkman-Forchheimer extended Darcy model.A uniform heat source or sink is presented in the solid phase.By applying similarity analysis,the governing partial differential equations are transformed into a set of time dependent non-linear coupled ordinary differential equations and they are solved numerically by Runge-Kutta Fehlberg method along with shooting technique.The obtained results are displayed graphically to illustrate the influence of different physical parameters on the velocity,temperature profile and heat transfer rate for both fluid and solid phases.Moreover,the numerical results obtained in this study are compared with the existing literature in the case of LTE and found that they are in good agreement.

Natural Convection in a Concentric Annulus:A Lattice Boltzmann Method Study with Boundary Condition-Enforced Immersed Boundary Method

In this paper,a boundary condition-enforced IBM is introduced into the LBMin order to satisfy the non-slip and temperature boundary conditions,and natural convections in a concentric isothermal annulus between a square outer cylinder and a circular inner cylinder are simulated.The obtained results show that the boundary condition-enforced method gives a better solution for the flow field and the complicated physics of the natural convections in the selected case is correctly captured.The calculated average Nusselt numbers agree well with the previous studies.

Numerical study of Natural Convection of Magnetic Fluids in a Cubic Cavity with a Heat Generating Object Inside by the Lattice Boltzmann Method

In this article,natural convection of a magnetic fluid in a cubic cavity with a heat generating object inside and under a uniform magnetic field is simulated by the lattice Boltzmann method.Results obtained from the present simulations are shown to be agreed well with our experimental measurements,and reveal more of effects of the magnetic field on the flow and heat transfer of the magnetic fluids.