Convection of Maxwell fluid over stretching porous surface with heat source/sink in presence of nanoparticles:Lie group analysis

The convection of a Maxwell fluid over a stretching porous surface with a heat source/sink in the presence of nanoparticles is investigated. The Lie symmetry group transformations are used to convert the boundary layer equations into coupled nonlinear ordinary differential equations. The ordinary differential equations are solved numerically by the Bvp4c with MATLAB, which is a collocation method equivalent to the fourth-order mono-implicit Runge-Kutta method. Furthermore, more attention is paid to the effects of the physical parameters, especially the parameters related to nanoparticles, on the temperature and concentration distributions with consideration of permeability and the heat source/sink.

Effects of nonlinear velocity slip and temperature jump onpseudo-plastic power-law fluid over moving permeable surface in presence of magnetic field

Flow and heat transfer of a pseudo-plastic power-law fluid over a stretching permeable surface with the magnetic effect is investigated. In the boundary conditions,the nonlinear temperature jump and the velocity slip are considered. Semi-similarity equations are obtained and solved by bvp4c with MATLAB. The problem can be considered as an extension of the previous work done by Mahmoud(Mahmoud, M. A. A. Slip velocity effect on a non-Newtonian power-law fluid over a moving permeable surface with heat generation. Mathematical and Computer Modelling, 54, 1228–1237(2011)). Efforts are made to discuss the effects of the power-law number, slip velocity, and temperature jump on the dimensionless velocity and temperature distribution.

Non-Newtonian biomagnetic fluid flow through a stenosed bifurcated artery with a slip boundary condition

The effects of a velocity slip and an external magnetic field on the flow of biomagnetic fluid(blood)through a stenosed bifurcated artery are investigated by using ANSYS FLUENT.Blood is regarded as a non-Newtonian power-law fluid,and the magnetization and electrical conductivity are considered in the mathematical model.The no-slip condition is replaced by the first-order slip condition.The slip boundary condition and magnetic force are compiled in the solver by the user-defined function(UDF).Numerical solutions are obtained by the finite volume method based on a nonuniform grid structure.The accuracy and efficiency of the solver are verified through a comparison with the literature.The results are presented graphically for different parameter values,and the effects of the magnetic number,the magnetic source position,the vascular obstruction ratio,the slip parameter,and the power-law index on the flow and temperature fields are illustrated.

不同几何形状的拱形支撑结构表面风压研究

本文评估了拱形支撑结构周围的风流场特性,属于计算流体动力学的研究领域.通过与文献中风洞试验数据的对比,验证了数值模拟结果.本文不但给出了不同形状拱形支撑结构(尖顶、扁平和拱形结构)表面的平均、脉动、最大和最小风压系数,而且讨论了不同的风向和结构高径比对风压系数的影响.结果表明,与其他结构相比,尖顶结构表面的风压系数和湍流扰动在数值上较低.地形粗糙度指数越低,结构表面的平均风压系数越大.此外,对于尖顶结构,高径比的增加会导致结构表面风压的增加.与其他风向相比,来风角度为45°的情况下屋顶表面所受负风压最强.值得指出的是,本文对于不同风向和尖顶结构的详细研究结果可以对工程设计优化领域有一定的借鉴意义.

A Study of Multiple Solutions for the Navier-Stokes Equations by a Finite Element Method

In this paper,a finite element method is proposed to investigate multiple solutions of the Navier-Stokes equations for an unsteady,laminar,incompressible flow in a porous expanding channel.Dual or triple solutions for the fixed values of the wall suction Reynolds number R and the expansion ratioαare obtained numerically.The computed multiple solutions for the symmetric flow are validated by comparing them with approximate analytic solutions obtained by the similarity transformation and homotopy analysis method.Unlike previous works,our method deals with the Navier-Stokes equations directly and thus has no similarity and other restrictions as in previous works.Finally we use the method to study multiple solutions for three cases of the asymmetric flow(which has not been studied before using the similarity-type techniques).

On the process of filtration of fractional viscoelastic liquid food

In the process of filtration,fluid impurities precipitate/accumulate;this results in an uneven inner wall of the filter,consequently leading to non-uniform suction/injection.The Riemannian-Liouville fractional derivative model is used to investigate viscoelastic incompressible liquid food flowing through a permeable plate and to generalize Fick's law.Moreover,we consider steady-state mass balance during ultrafiltration on a plate surface,and a fractional-order concentration boundary condition is established,thereby rendering the problem real and complex.The governing equation is numerically solved using the finite difference algorithm.The effects of the fractional constitutive models,generalized Reynolds number,generalized Schmidt number,and permeability parameter on the velocity and concentration fields are compared.The results show that an increase in fractional-orderαin the momentum equation leads to a decrease in the horizontal velocity.Anomalous diffusion described by the fractional derivative model weakens the mass transfer;therefore,the concentration decreases with increasing fractional derivativeγin the concentration equation.