Mathematical modelling of couple stresses on fluid flow in constricted tapered artery in presence of slip velocity-effects of catheter

This paper explores the mathematical model for couple stress fluid flow through an annular region. The above model is used for studying the blood flow be-tween the clogged （stenotic） artery and the catheter. The asymmetric nature of the stenosis is considered. The closed form expressions for the physiological parameters such as impedance and shear stress at the wall are obtained. The effects of various geomet-ric parameters and the parameters arising out of the fluid considered are discussed by considering the slip velocity and tapering angle. The study of the above model is very significant as it has direct applications in the treatment of cardiovascular diseases.     

波浪扰动下河口幂律异重流的动力场分布特性

河口底层浮泥异重流的运动特性对于河口维持以及港口航道泥沙淤积过程具有重要的作用, 是海岸学科研究的关键内容, 也是热点内容之一. 本文首先综述了河口泥沙异重流研究的重要意义, 分析并总结了各家异重流理论模型的不同点和适应条件; 其次, 根据本文研究问题的实际需要, 构建了波浪与底泥相互作用的双层流体理论分析模式, 将上层流体简化为常见的牛顿体, 而将下层流体的流变关系设置为幂律函数, 研究了波浪作用下河口底部幂律异重流的流场特性. 这些特性包括：波浪速度场、底泥运动的流速场、不同密度影响下的压力场以及异重流泥面波与表面 波的波幅比等, 分析了泥层密度、波动圆频率以及底泥幂律指数对流场及界面波的影响. 研究发现, 在波浪扰动下, 两层流体交界处速度分量连续, 压强出现突变. 在下部泥层中, 水平速度幅值曲线存在极大值. 随着波动圆频率增加以及泥层密度与流动指数的减小, 界面处上下压强差值呈现增大的趋势. 本模型与实测波幅比的数据进行对比结果证实了模型的合理性.     

Steady Ostwald flow between two differentially rotating co-axial discs

The steady flow of a power-law (Ostwald) fluid between two differentially rotating, parallel, co-axial discs has been considered for both large and small Reynolds number. All edge effects of the discs are neglected, the discs rotate in the same sense and the distance between the two discs is much smaller than their radius. In the large Reynolds number case a similarity solution is sought. It is assumed that the flow consists of boundary layers on the discs, while the core rotates as a rigid body with speed intermediate of those of the discs. The boundary layer is thinner than in the equivalent Newtonian problem, and the decay of the boundary layers is found to be algebraic. This slow decay contrasts with the faster exponential decay in the Newtonian case. For the low Reynolds number problem, the ratio of the disc separation to radius was taken to be much smaller than the Reynolds number. This is, in effect, a lubrication-type problem. The velocity components are expressed as expansions in ascending powers of the Reynolds number. For both the large and small Reynolds number flow, the torque is calculated as a function of the disc speeds, for various values of the power-law index n.     

磁性流体密封磁场的解耦计算

分析了磁性流体密封中的磁场与力场的耦合问题,采用边界逼近的迭代方法准确计算了磁场分布,进而求出了密封压差,分析了解耦计算与线性计算的差别.结果表明,随着磁性流体磁化强度的提高,解耦计算与线性计算的差别增大.     

Derivation of Matching Conditions at the Contact Surface Between Fluid-Saturated Porous Solid and Bulk Fluid

The compatibility conditions matching macroscopic mechanical fields at the contact surface between fluid-saturated porous solid and adjacent bulk fluid are considered. Special attention is paid to the derivation of conditions for tangential components of the fluid flow velocities and to the verification of validity of the condition postulated by Beavers and Joseph. It has been shown that at the contact surface between two media, a dissipation of mechanical energy due to the fluid viscosity does exist and thus the form of a dissipation function has been proposed. It has been proven that this relation determines the form of two linear compatibility conditions derived for the tangential components of the relative fluid velocities and that these conditions describe the experimental results more precisely than the condition postulated by Beavers and Joseph.     

GPU accelerated simulations of three-dimensional flow of power-law fluids in a driven cube

Newtonian fluid flow in two- and three-dimensional cavities with a moving wall has been studied extensively in a number of previous works. However, relatively a fewer number of studies have considered the motion of non-Newtonian fluids such as shear thinning and shear thickening power law fluids. In this paper, we have simulated the three-dimensional, non-Newtonian flow of a power law fluid in a cubic cavity driven by shear from the top wall. We have used an in-house developed fractional step code, implemented on a Graphics Processor Unit. Three Reynolds numbers have been studied with power law index set to 0.5, 1.0 and 1.5. The flow patterns, viscosity distributions and velocity profiles are presented for Reynolds numbers of 100, 400 and 1000. All three Reynolds numbers are found to yield steady state flows. Tabulated values of velocity are given for the nine cases studied, including the Newtonian cases.     

波浪扰动下河口幂律异重流的动力场分布特性

河口底层浮泥异重流的运动特性对于河口维持以及港口航道泥沙淤积过程具有重要的作用, 是海岸学科研究的关键内容, 也是热点内容之一. 本文首先综述了河口泥沙异重流研究的重要意义, 分析并总结了各家异重流理论模型的不同点和适应条件; 其次, 根据本文研究问题的实际需要, 构建了波浪与底泥相互作用的双层流体理论分析模式, 将上层流体简化为常见的牛顿体, 而将下层流体的流变关系设置为幂律函数, 研究了波浪作用下河口底部幂律异重流的流场特性. 这些特性包括:波浪速度场、底泥运动的流速场、不同密度影响下的压力场以及异重流泥面波与表面 波的波幅比等, 分析了泥层密度、波动圆频率以及底泥幂律指数对流场及界面波的影响. 研究发现, 在波浪扰动下, 两层流体交界处速度分量连续, 压强出现突变. 在下部泥层中, 水平速度幅值曲线存在极大值. 随着波动圆频率增加以及泥层密度与流动指数的减小, 界面处上下压强差值呈现增大的趋势. 本模型与实测波幅比的数据进行对比结果证实了模型的合理性.      

Variable fluid properties and thermal radiation effects on flow and heat transfer in micropolar fluid film past moving permeable infinite fiat plate with slip velocity

This work deals with the influence of thermal radiation on the problem of the mixed convection thin film flow and heat transfer of a micropolar fluid past a moving infinite vertical porous flat plate w...