FREE CONVECTION FLOW OF WATER AT 4℃ PASSING AN INFINITE POROUS PLATE WITH CONSTANT SUCTION IN A ROTATING SYSTEM

In this work an analysis of steady free convection flow of waterat 4℃ passing a vertical infinite porous plate in a rotating systemis considered.Approximate solutions for the coupled nonlinear equa-tions are obtained for the velocity and the temperature.The effectof E’(Eckman number) is discussed,when P (Prandtl number)=11.4,which corresponds to water at 4℃.     

HIGHER-ORDER THEORY OF INTERNAL SOLITARY WAVES WITH A FREE SURFACE IN TWO-LAYER FLUID SYSTEM OF FINITE DEPTH

A higher-order approximation theory of internal solitary waves with a frre surface ispresented.Using the method of strained co-ordinates,the third-order approximationevolution equation of interface has been found.An analytic expression of the wave velocityis given.The evolution equation has been solved numerically.It is found that the effects offree surface on the shape and wave velocity of solitary wave are O(ε_2),and the third-order numerical solutions,are closer to experimental data than the first-and second-ordersolutions.     

THE NUMERICAL SOLUTION OF THE UNSTEADY NATURAL CONVECTION FLOW IN A SQUARE CAVITY AT HIGH RAYLEIGH NUMBER USING SADI METHOD

The unsteady natural convection flow in a square cavity at high Rayleigh numberRa=10~7 and 2×10~7 has been computed using cubic spline integration.The requiredsolutions to the two dimensional Navier-Stokes and energy equations have been obtainedusing two alternate numerical formulations on non-uniform grids.The main features of thetransient flow have been briefly discussed.The results obtained by using the present methodare in good agreement.with the theoretical predictions.The steady state results havebeen compared with accurate solutions presented recently for Ra=10~7.     

THE BNARD CONVECTION IN A LAYER OF FLUID WITH A TIME-DEPENDENT MEAN TEMPERATURE

The onset of Benard convection. or the critical Rayleigh number in a layer of fluid witha time-dependent mean temperature has been investigated theoretically. The criticalRayleigh number is regarded as a function of time and is expanded in series of a smallparameter. Up to second approximation a simple expression of critical Rayleigh number isobtained for the time region for away from the point of zero.     

NUMERICAL INVESTIGATION ON FLOW STABILITY OF RAYLEIGH-B?NARD CONVECTION OF COLD WATER IN A RECTANGULAR CAVITY COOLED AND HEATED SYMMETRICALLY RELATIVE TO THE TEMPERATURE OF DENSITY MAXIMUM

为了解具有密度极值流体瑞利-贝纳德对流特有现象和规律,利用有限容积法对长方体腔内关于密度极值温度对称加热-冷却时冷水瑞利-贝纳德对流的分岔特性进行了三维数值模拟,得到了不同条件下的对流结构型态及其分岔序列,分析了密度极值特性、瑞利数、热边界条件以及宽深比对瑞利-贝纳德对流的影响. 结果表明:具有密度极值冷水瑞利-贝纳德对流系统较常规流体更加稳定,且流动型态及其分岔序列更加复杂;相同瑞利数下多种流型可以稳定共存,各流型在相互转变中存在滞后现象;随着宽深比的增加,流动更易失稳,对流传热能力增强;系统在导热侧壁时比绝热侧壁更加稳定,对流传热能力有所减弱;基于计算结果,采用线性回归方法,得到了热壁传热关联式.     

A CLOSED SYSTEM OF EQUATIONS FOR DENSE TWO-PHASE FLOW AND EXPRESSIONS OF SHEARING STRESS OF DISPERSED PHA’E AT A WALL

In this paper.each of the two phases in dense two-phase flow is considered ascontinuous medium and the fimdamental equations for two-phase flow are described inEulerian form.The generalized constitutive relation of the Bingham fluid is applied to thedispersed phase with the analysis of physical mechanism of of dense two-phase flow.Theshearing stress of dispersed phase at a wall is used to give a boundary condition.Then amathematical model for dense two-phase flow is obtained.In addition.the expressions ofshearing stress of dispersed phase at a wall is derived according to the fundamental,model ofthe frictional collision between dispersed-phase particles and the wall.