Influence of stress releasing ratio and boundary scope on 2D FEM simulate

Give constrains of costs and technology in analysis,actual practice of 2D FEM is widely popular and demanded.In order to take advantage of 2D FEM to simulate 3D stress state,the concept of stress releasing ratio was generally introduced to represent the 3D constraint effect.For example,the simulation analysis of tunnel excavation is based on the measured actual deformation to provide stress releasing ratio.In the engi- neering of open excavation,the construction is,most of the case,targeted on alluvial de- posit with relatively soft stratum.However,the 2D FEM simulation lacks a clear and ra- tional basis in how to represent the effects of 3D constraint.Thus,in order to investigate the problem above,the author analyzed same engineering using both 2D and 3D individu- ally,and compared the corresponding results.Based on the 3D analysis,factors including the relationship between the model's scope,stress releasing ratio,and construction condi- tion of 2D analysis were also examined.

Experimental Study of Design and Implementation of Small-Scale Biogas Digest System

The main purpose of this study is to design and implement a small-scale biogas digest system, which can provide a certain amount of natural gas (N.G.). The percentage of methane gases emissions according to the various research studies is around 25% of the total emission gases of the waste materials. For all industrialized nations, food waste costs approximately $680 billion/year. The dramatic increase in population and the waste of organic and non-organic materials lead to the use of biomass energy as the source of the renewable energy system to produce a natural gas (N.G.), which can be utilized in cooking or commercialized for the public. The burn out of the waste and the garbage materials causes tremendous pollution and global warming;however, utilizing the Biogas Digest System (BDS) will stop polluting the surrounding environment. The amount of natural gases production was measured for various atmospheric conditions. The important findings of this study are the amount of N.G., which can be increased by mixing two different types of organic waste materials.

纳米流体在顶部开孔底部加热的四方形容器内的三维自然对流（英文）

构建纳米流体在顶部开孔底部加热的四方形容器流动模型,基于有限体积法,进行了纳米流体三维自然对流的数值研究。得到的控制参数为纳米粒子浓度(φ)0~0.05、前后壁倾角(α)5°~75°、Rayleigh数10^3~10^5、加热器的换热器长度0.1~1。结果表明,倾角和纳米颗粒的体积分数影响流动结构,提高了传热效果。

Numerical Study Using Statistical and Quantum Approaches for Solving Energy and Navier Stokes Momentum Equations (PDEs)

Statistical and Quantum numerical method was implemented in this study to solve various cases in partial differential equations (PDEs) in engineering applications. One-dimensional with two lattices arrangements as well as two-dimensional with nine lattices arrangements is employed. The stability and the accuracy have been investigated either using statistical technique or using Euler’s method. The numerical limitations of using LBM method have been obtained and compared with those obtained by Euler’s method finite difference method. The main goal of this study is to investigate the ability of a statistical method in solving various ODEs or PDEs in energy and momentum equations and comparing them with those obtained by a classical numerical technique. The results show the ability of the statistical method for solving ODEs and PDE’s with more stable and accurate results. Therefore, the motivation of utilizing the statistical technique is the stability and it is easy for a complex fluid flow application.

Dissipative flow features of Carreau nanofluid with thermal radiation inside plane wall channel:Jeffery-Hamel analysis

The current article communicates a numerical investigation on laminar flow of dissipative generalized Newtonian Carreau nanofluid flowing through vertical conduit with converging and diverging plane walls.Thermal and concentration characteristics due to enthalpy change,activation energy,and non-linear thermal radiation have been examined in the presence of buoyancy forces.The channel walls for both temperature and volumetric fraction are assumed to be isothermal.The instability mechanism of nanofluids is reported using a two-phase nanofluid model,which works reasonably well for nanoparticle concentrations below a certain threshold.A Jeffery-Hamel(J-H)flow model is developed by assuming an incompressible purely radial flow of Carreau nanofluids with heat and mass transportation.Using the suitable non-dimensional variables,the resulting nonlinear partial differential equations are turned into a system of ordinary differential equations.The modified governing equations are then numerically solved using the built-in boundary value problem solver bvp4c,on the template form of commercial software MATLAB.The impacts of material,geometrical and thermophysical parameters governing the J-H problem are discussed and illustrated.Results indicate that higher buoyance forces incline the velocity profiles in converging enclosure,while a slight reduction is perceived in opposing forces.A significant decrease of wall heat transmission is reflected for larger values of activation energy and radiation parameter.For endorsing this communication,a comparison analysis is established with existing research and noticed a remarkable agreement.Practically,the flow inside converging and diverging channels are deployed in nuclear reactors that use plate-type nuclear energies,high heat-flux condensed heat exchangers,high-performance micro-electronic cooling systems,jets,rockets nozzles,and jet propulsion inlet.

The Method of Fundamental Solutions for Solving Exterior Axisymmetric Helmholtz Problems with High Wave-Number

In this paper,we investigate the method of fundamental solutions(MFS)for solving exterior Helmholtz problems with high wave-number in axisymmetric domains.Since the coefficientmatrix in the linear system resulting fromtheMFS approximation has a block circulant structure,it can be solved by the matrix decomposition algorithm and fast Fourier transform for the fast computation of large-scale problems and meanwhile saving computer memory space.Several numerical examples are provided to demonstrate its applicability and efficacy in two and three dimensional domains.