Dissipative heat for the Casson fluid flow past an expanding cylindrical surface

A non-Newtonian model is developed by considering the flow of non-Newtonian Casson fluid past an expanding cylinder embedded in a porous medium. The novelty arises because of the conjunction of dissipative heat, and the additional heat source that enriches the heat transport phenomenon significantly. The application of the study is vital due to the flow of blood through the artery, a physiological study. Therefore, the study of Casson fluid plays an important role. The nonlinear partial differential equations that appeared in the formulation are now renovated to the coupled nonlinear ordinary differential equations. However, a numerical technique associated with shooting-based followed by Runge–Kutta fourth-order is employed for the solution of these transformed equations. The uniqueness of diverse pertinent parameters on the flow phenomena is scrutinized through graphs and numerically simulated results presented in tables. The important observations are as follows; the magnetic parameter and permeability augment the shear rate coefficients, whereas the Casson parameter rendered the opposite impact. Furthermore, the non-Newtonian Casson parameter retards the fluid temperature, and the curvature parameter significantly enhances it.     

Influences of Soret and Dufour numbers on mixed convective and chemically reactive Casson fluids flow towards an inclined flat plate

The purpose of this study is to examine the magnetohydrodynamic mixed convection Casson fluid flow over an inclined flat plate along with the heat source/sink. The present flow problem is considered under the assumption of the chemical reaction and thermal radiation impacts along with heat and mass transport. The leading nonlinear partial differential equations of the flow problem were renovated into the nonlinear ordinary differential equations (ODEs) with the assistance of appropriate similarity transformations and then we solved these ODEs with the employment of the bvp4c technique using the computational software MATLAB. The consequences of numerous leading parameters such as thermophoretic parameter, local temperature Grashof number, solutal Grashof number, suction parameter, magnetic field parameter, Prandtl number, chemical reaction parameter, Dufour number, Soret number, angle of inclination, radiation parameter, heat source/sink, and Casson parameter on the fluid velocity, temperature, and concentration profiles are discoursed upon  and presented through different graphs. Some important key findings of the present investigation are that the temperature of the Casson fluid becomes lower for local temperature Grashof number and solutal Grashof number. It is initiated that the Casson fluid parameter increases the velocity of the fluid whereas the opposite effect is noticed in the temperature profile. Higher estimation of Prandtl number and magnetic parameter elevated the Casson fluid concentration. Finally, the skin friction coefficient, Nusselt number, and Sherwood number are calculated and tabulated. It is also examined that the Nusselt number is weakened for both the Dufour number and Soret number but the skin fraction coefficient is greater for both the Dufour number and Soret number.     

Modeling and Experiments on Electromagnetic Separation of Inclusions from Aluminum Melt under Combined Magnetic Field

复合磁场是金属电磁净化的一种新方法,通过实验和数值模拟,研究由旋转磁场和行波磁场组成的复合磁场电磁净化的效果。装置模型由2组三相交流线圈组构成,通过有限元法分别计算旋转磁场、行波磁场及其复合磁场作用下的电磁体积力、流场分布。结果显示,旋转磁场电磁力使得流场水平转动,下行波磁场电磁力分布驱动外壁容易向下运动,在中心形成向上束流;而复合磁场则兼具两者效果。数模拟数据与实验结果吻合度较好。为了探讨复合磁场电磁净化的机理,计算熔体中第二相夹杂物的体积分布和模拟颗粒在熔体中的运动轨迹。分析结果表明:流场和阿基米德力是影响颗粒运动的2个主要因素;复合磁场相对于单一磁场具有更优越的净化效果。     

热等离子体裂解甲烷制乙炔过程的数值模拟

针对热等离子体甲烷裂解过程,建立了直流电弧反应器的数值模型,使用磁流体力学理论对反应器内的电弧和流场进行数值模拟,考察了电弧运动变化的规律和射流场特点,并分别耦合热力学平衡模型和宏观动力学模型探索了裂解反应的特点及其与电弧的相互影响关系。结果表明反应器内电弧做规律运动和形态变化,惰性无反应气氛下电弧形态变化不显著,运动平稳。放电区发生反应时,一方面气体的组成及热力学性质发生迅速变化,气体放电特性受到影响,等离子体的稳定性下降,化学反应是等离子体不稳定性的重要来源。另一方面,反应和扩散的特征时间小于电弧运动变化的特征时间,各物质在空间的分布较为均匀,受温度场非均匀性的影响较小,模拟的甲烷转化率和乙炔收率与实验结果相近。本工作尤其是等离子体物理模型与甲烷裂解化学反应模型的耦合,为理解热等离子体裂解相关过程提供了直接的帮助和指导。     

Steady incompressible magnetohydrodynamics Casson boundary layer flow past a permeable vertical and exponentially shrinking sheet: A stability analysis

Steady incompressible magnetohydrodynamic mixed convection boundary layer flow of a Casson fluid on an exponentially vertical shrinking sheet using the non‐Newtonian heating equation is investigated in this paper. There are three main objectives of this study, namely, to develop a new mathematical model, to obtain multiple solutions, and to perform stability analysis. The governing partial differential equations have been changed into nonlinear ordinary differential equations. The resultant equations of boundary value problems are then converted into the equivalent initial value problems using the shooting method before they can be solved using Runge‐Kutta of order four. The numerical results are obtained and found to be in good agreement with the published literature. The results also indicate that the velocity boundary layer becomes thinner as the magnetic, slip, and Casson parameters increase. Dual solutions for temperature and velocity distributions are obtained. Furthermore, the results suggest that the presence of the force of buoyancy (opposing flow case) would cause the occurrence of dual solutions. However, based on the stability analysis, only the first solution is stable.     

Numerical exploration of thermal radiation and Biot number effects on the flow of a non‐Newtonian MHD Williamson fluid over a vertical convective surface

A theoretical and computational study of the magnetohydrodynamic flow and free convection heat transfer in an electroconductive polymer on the external surface of a vertical plate under radial magnetic field is presented. The Biot number effects are considered at the vertical plate surface via modified boundary conditions. The Williamson viscoelastic model is employed which is representative of certain industrial polymers. The nondimensional, transformed boundary layer equations for momentum and energy are solved with the second‐order accurate implicit Keller box finite difference method under appropriate boundary conditions. Validation of the numerical solutions is achieved via benchmarking with earlier published results. The influence of Weissenberg number (ratio of the relaxation time of the fluid and time scale of the flow), magnetic body force parameter, stream‐wise variable, and Prandtl number on thermo fluid characteristics are studied graphically and via tables. A weak elevation in temperature accompanies increasing Weissenberg number, whereas a significant acceleration in the flow is computed near the vertical plate surface with increasing Weissenberg number. Nusselt number is reduced with increasing Weissenberg number. Skin friction and Nusselt number are both reduced with increasing magnetic field effect. The model is relevant to the simulation of magnetic polymer materials processing.     

电磁冶金

本文对电磁冶金的发展概况作了概要阐述着重介绍了电磁流体力学基本理论的研究及其在冶金中的应用，文中对电磁感应流的基本式，电磁感应流的分析，电磁力对凝固组织的影响以及用高频磁场控制熔融金属的形状等均作了明确的论述此外，对磁流体力学用于材料方面的磁场处理的分类及其体系也作了系统说明     

新型大功率电磁脉冲形成与发射技术研究

高功率电磁脉冲是地球物理研究、地质勘探、石油开采以及电子对抗和微波武器等军事领域极具潜在应用价值的技术。在讨论传统脉冲磁流体动力( MHD)系统和现代脉冲MHD的基础上,探讨了基于火药燃烧的大功率脉冲形成与发射技术,着重研究了低压单脉冲MHD输出转换为大功率多脉冲电磁能的方法和实现电路,给出了实验结果,并对实现该系统的一些关键问题进行了阐述。     

磁稳定床反应器重整生成油后加氢过程研究

对采用非晶态合金催化剂SRNA－4的磁稳定床反应器重整生成油后加氢精制过程进行了研究，试验考察了各种条件对加氢效果的影响，找到适宜的反应条件为：反应温度80－120℃，压力1．0－1．5MPa，液时空速20－30h^-1，氢油体积比20－100及磁场强度15－20kA/m。并建立了反应器模型。研究结果表明，在磁稳定床反应器中可以重整生成油的溴值从2．0gBr(100g) 降到0．5gBr(100g) 以下，基本无芳烃损失，满足工业要求。磁稳定床重整生成油后加氢工艺与传统固定床后加氢工艺及白土精制工艺相比，具有催化剂装卸方便、反应条件缓和、空速大等优点。