Steady flow of a power-law fluid past a cylinder

Summary Considered in this paper is the two-dimensional steady flow of a power-law fluid past a stationary circular cylinder. The governing nonlinear equations, expressed in terms of a stream function and vorticity, were solved by finite differences for Reynolds numbers (based on the radius of the cylinder)R=5,20, 40 for various power-law indices,n. Parameters such as the drag coefficient, separation angle, wake length and critical Reynolds number are presented and contrasted with those of a Newtonian fluid (n=1) to illustrate the non-Newtonian effects. For a given-Reynolds number a consistent behaviour withn was observed in the parameters for the ranges considered. The results obtained for the Newtonian case agree well with documented results.     

Spiral motion of a cylinder in a power-law non-newtonian fluid

A study is made of steady-state flow in a power-law system in the presence of double shear caused by spiral motion of a circular cylinder.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 18, No. 5, pp. 810–814, May, 1970.     

Magnetohydrodynamic flow for a non-Newtonian power-law fluid having a pressure gradient and fluid injection

Summary The nonlinear partial differential equation of motion for an incompressible, non-Newtonian power-law fluid flowing over flat plate under the influence of a magnetic field and a pressure gradient, and with or without fluid injection or ejection, is transformed to a nonlinear third-order ordinary differential equation by using a stream function and a similarity transformation.The necessary boundary conditions are developed for flow with and without fluid injection (or ejection), and a solution for four different power-law fluids, including a Newtonian fluid, is presented.The controlling equation includes, as special cases, the Falkner-Skan equation and the Blasius equation.     

Stability of the circular couette flow of a power-law fluid

The stability of the circular Couette flow of a non-Newtonian power-law fluid is analyzed in the small-gap approximation.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 24, No. 4, pp. 719–724, April, 1973.     

丝网印版的分辨率特性研究

分析了丝网目数、丝径等几何参数及网版的厚度、粗糙度对丝网印刷精度的影响;对网版制作过程中的丝网选择,网版涂布曝光等注意事项做了研究,为获得高质量的网版提供了理论依据。对实际生产具有重要指导意义。     

Nonisothermal generalized couette flow of a fluid with a power-law rheological characteristic

The nonisothermal steady flow of a power-law fluid between two parallel plates is analyzed for different kinds of temperature boundary conditions and, moreover, with energy dissipation taken into account. It is assumed that the fluidity of the substance is a linear function of the temperature.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol.22, No. 5, pp. 872–880, May, 1972.     

Flow of a second-order fluid over a stretching surface having power-law temperature

Summary The important physical quantities such as the coefficients of skin-friction and heat transfer are obtained from the closed-form solutions for the boundary layer equations of the flow of a second-order fluid over a stretching surface having power-law temperature.     

Flow analysis of a power-law fluid confined in an extrusion die

The one-dimensional equations in cylindrical coordinates governing flow in an arbitrary cross-sectional shape of a cavity and the slot are derived by accounting of the order of magnitude of terms by using scaling arguments and asymptotic techniques. The derived equation is based on an average momentum and mass balance within the cavity. The one-dimensional equations governing flow in a single-cavity die which can be used to predict the geometry of the cavity and the film thickness deviations for given geometry and operating points and thus yield a design strategy for extrusion die optimized for specific applications. The derived one-dimensional governing equations with the exception of coordinates system for extrusion dies are found to be identical to that of Leonard [Polym. Eng. Sci. 25 (9) (1985) 570] and Weinstein and Ruschak [AIChE J. 42 (9) (1996) 2401] who used the shape factor in the different manner and can be reduced to Miller’s [Ind. Eng. Chem. Fundam. 11 (4) (1972) 524] simple model under the certain restrictions.     

The thermal boundary layer of a non-fourier power-law fluid on a plate with a variable surface temperature

The equation for the thermal boundary layer of a non-Fourier powerlaw fluid on a flat plate with an exponential distribution of surface temperature is reduced to an ordinary equation and solved by the method of finite differences. The effect of the exponent on the temperature profile and on the heat-transfer coefficient is determined. It is demonstrated that the asymptotic solutions of the equation for large are nearly exact.     

Nonlinear power-law resistance fluid filtration through porous semispace with a groove

A method is proposed for solving some planar problems of nonlinear filtration with powerlaw resistance in the case of straight-line boundaries of the filtration region.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 20, No. 4, pp. 717–724, April, 1971.     

Momentum and heat transfer from a continuous moving surface to a power-law fluid

Summary Momentum and heat transfer from a continuous moving surface with an arbitrary surface velocity distribution and uniform surface temperature in a power-law fluid have been considered. Using a coordinate transformation, the boundary layer equations are reduced to a simple form. Modified Merk's series method has been used for momentum equation and universal function approach for energy equation. The resulting equations have been integrated numerically by using fourth-order Runge-Kutta method and method of continuation. Two types of plate velocity distributions are considered: (i) surface velocity proportional to positive power of distance from the slot, (ii) linearly stretched velocity distribution with nonzero slot velocity. It is found that the displacement thickness is much thicker for pseudoplastic fluids than for Newtonian and dilatant fluids for both cases. The local Nusselt number, obtained by the universal function method, has been compared with non-similar results. The results are in good agreement.     

用丝网印刷法制备Pt电极及其性能

采用单层和双层印刷法在氧化铝衬底上制备功能陶瓷厚膜用Pt电极,研究了烧结温度、升温速率和电极厚度对Pt电极层的表面形貌、表面覆盖率和表面粗糙度的影响,以揭示晶粒长大、气孔生长及致密化机制.结果表明,在单层印刷Pt电极的烧结过程中,低温阶段残留的碳使不同温区Pt的主导扩散机制不同.双层印刷Pt电极中第一层在600℃下烧结后,印刷第二层再在1200℃下烧结具有最大表面覆盖率和最小平均粗糙度(其值约为0.82 μm),同时具有最好的导电性能(方阻为0.044 Ω/□).     

Analytical solutions of hydromagnetic boundary-layer flow of a non-Newtonian power-law fluid past a continuously moving surface

Summary The boundary-layer flow of a power-law non–Newtonian fluid over a continuously moving surface in the presence of a magnetic field B(x) applied perpendicular to the surface has been investigated. An analytical solution is obtained and compared with the numerical solution of the resulting non linear ordinary differential equation. The effects of the Stewart number (N) and the power law-index (n) on the velocity profiles and the skin-friction are studied.     

Hydrodynamic flow stability of a fluid with a power-law rheological behavior in a channel with elastic walls

The stability of steady gradiental flow of a non-Newtonian fluid with a power-law rheological behavior in a channel with elastic walls is analyzed.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 24, No. 6, pp. 1099–1102, June, 1973.     

Facile synthesis of silver malonate conductive MOD ink for screen printing

At present, screen printing is the most widely used technique in the printed electronics industry and the printed pattern can satisfy certain electronic application requirements. Ink development is the most important part of the printing process. In this paper, a new particle-free MOD ink (MOD?=?metal–organic-decomposition) was synthesized from silver malonate, diethanolamine (DEA) and ethylene glycol (EG). Silver malonate was the precursor of silver. DEA was the complexing agent that maked silver malonate soluble. EG acted not only as a solvent to regulate the rheological properties of the ink, but also as a reducing agent to reduce silver ions. The decomposition temperature was reduced from 210 °C to about 100 °C by the formation of silver-amine complex, thus the selection range of substrate could be broadened. The ink was spread on the polyimide (PI) substrate by screen printing. The silver film was formed after heat treatment at 150 °C for 1 h and its electrical conductivity can reach 1.0?×?10⁴ S cm^?1, which corresponded to one sixty-third of the theoretical conductivity of the bulk silver (6.3?×?10⁵ S cm^?1).

     

Fabrication and sintering of Pt electrode deposited by screen printing method

采用单层和双层印刷法在氧化铝衬底上制备功能陶瓷厚膜用Pt电极, 研究了烧结温度、升温速率和电极厚度对Pt电极层的表面形貌、表面覆盖率和表面粗糙度的影响,以揭示晶粒长大、气孔生长及致密化机制. 结果表明, 在单层印刷Pt电极的烧结过程中,低温阶段残留的碳使不同温区Pt的主导扩散机制不同.双层印刷Pt电极中第一层在600℃下烧结后,印刷第二层再在1200℃下烧结具有最大表面覆盖率和最小平均粗糙度(其值约为0.82 um),同时具有最好的导电性能(方阻为0.044 Ω/□).     

Unsteady boundary layer flow of power-law fluid on stretching sheet surface

Two-dimensional unsteady boundary layer equations of non-Newtonian fluids are treated. Flow of a thin fluid film of a power-law caused by stretching of surface is investigated by using a similarity transformation. By using this transformation, we reduce the unsteady boundary layer equations to a non-linear ordinary differential equation system. Numerical solutions of outcoming nonlinear differential equations are found by using a combination a Runge–Kutta algorithm and shooting technique. Boundary layer thickness is explored numerically for different values of power-law index.     

Electrochemistry in nanovials fabricated by combining screen printing and laser micromachining

The coupling of screen-printing and laser micromachining technology has been used to create a nanovial with "built-in" working and reference electrodes. The volume of the nanovial was calculated to be 7.2 nL using dimensions determined by SEM. The electrochemical nanovial was characterized using the ferri/ferrocyanide redox couple. Cyclic voltammetry and chronoamperometry experiments were performed with electrochemical nanovials utilizing 5% (v/v) glycerin in the solutions and a humidified headspace to control evaporation of the small-volume samples. Chronoamperometry experiments gave results consistent with a diffusion-limited process and revealed a working electrode surface area of 2.6 x 10(4) micron 2. The ultrasmall-volume cells represent a simple, reliable, low-cost approach for the fabrication of complete electrochemical nanovials.