NUMERICAL SIMULATION OF THREE DIMENSIONAL TURBULENT FLOW IN SUDDENLY EXPANDED RECTANGULAR DUCT

ＮＵＭＥＲＩＣＡＬＳＩＭＵＬＡＴＩＯＮＯＦＴＨＲＥＥＤＩＭＥＮＳＩＯＮＡＬＴＵＲＢＵＬＥＮＴＦＬＯＷＩＮＳＵＤＤＥＮＬＹＥＸＰＡＮＤＥＤＲＥＣＴＡＮＧＵＬＡＲＤＵＣＴＮＵＭＥＲＩＣＡＬＳＩＭＵＬＡＴＩＯＮＯＦＴＨＲＥＥＤＩＭＥＮＳＩＯＮＡＬＴＵＲＢＵ...     

ANALYTICAL SOLUTION OF RADIATED SOUND PRESSURE OF RING－STIFFENED CYLINDRICAL SHELLS IN FLUID MEDIUM

ＡＮＡＬＹＴＩＣＡＬＳＯＬＵＴＩＯＮＯＦＲＡＤＩＡＴＥＤＳＯＵＮＤＰＲＥＳＳＵＲＥＯＦＲＩＮＧ－ＳＴＩＦＦＥＮＥＤＣＹＬＩＮＤＲＩＣＡＬＳＨＥＬＬＳＩＮＦＬＵＩＤＭＥＤＩＵＭＸｉｅＧｕａｎｍｏ（谢官员模）ＬｕｏＤｏｎｇｐｉｎｇ（骆东平）（Ｒｅｃｅｉｖ...     

QUASI－FLOW CORNER THEORY ON LARGE PLASTIC DEFORMATION OF DUCTILE METALS AND ITS APPLICATIONS

ＱＵＡＳＩ－ＦＬＯＷＣＯＲＮＥＲＴＨＥＯＲＹＯＮＬＡＲＧＥＰＬＡＳＴＩＣＤＥＦＯＲＭＡＴＩＯＮＯＦＤＵＣＴＩＬＥＭＥＴＡＬＳＡＮＤＩＴＳＡＰＰＬＩＣＡＴＩＯＮＳＨｕＰｉｎｇ（胡平）ＬｉｕＹｕｑｉ（柳玉启）ＧｕｏＷｅｉ（郭威）ＴａｉＦｅｎｇ（台风）（Ｒ...     

MOTION EQUATIONS OF MULTILAYERED ELASTIC ELECTROCONDUCTIVE PLATES IN A MAGNETIC FIELD

ＭＯＴＩＯＮＥＱＵＡＴＩＯＮＳＯＦＭＵＬＴＩＬＡＹＥＲＥＤＥＬＡＳＴＩＣＥＬＥＣＴＲＯＣＯＮＤＵＣＴＩＶＥＰＬＡＴＥＳＩＮＡＭＡＧＮＥＴＩＣＦＩＥＬＤＧｏｕＸｉｎｇ－ｈｕａ（苟兴华）（ＳｉｃｈｕａｎＵｎｉｖｅｒｓｉｔｙ,Ｃｈｅｎｇｄｕ）ＺｈａｎｇＦａ...     

CONSTRUCTION OF MODIFIED TAYLOR－GALERKIN FINITE ELEMENTS AND ITS APPLICATION IN COMPRESSIBLE FLOW COMPUTATION

ＣＯＮＳＴＲＵＣＴＩＯＮＯＦＭＯＤＩＦＩＥＤＴＡＹＬＯＲ－ＧＡＬＥＲＫＩＮＦＩＮＩＴＥＥＬＥＭＥＮＴＳＡＮＤＩＴＳＡＰＰＬＩＣＡＴＩＯＮＩＮＣＯＭＰＲＥＳＳＩＢＬＥＦＬＯＷＣＯＭＰＵＴＡＴＩＯＮＣＯＮＳＴＲＵＣＴＩＯＮＯＦＭＯＤＩＦＩＥＤＴＡＹＬＯＲ...     

CHARACTERISTICS OF SUBDIFFERENTIALS OF FUNCTIONS

ＣＨＡＲＡＣＴＥＲＩＳＴＩＣＳＯＦＳＵＢＤＩＦＦＥＲＥＮＴＩＡＬＳＯＦＦＵＮＣＴＩＯＮＳ（郭兴明）ＣＨＡＲＡＣＴＥＲＩＳＴＩＣＳＯＦＳＵＢＤＩＦＦＥＲＥＮＴＩＡＬＳＯＦＦＵＮＣＴＩＯＮＳ￥ＧｕｏＸｉｎｇｍｉｎｇ（ＲｅｃｅｉｖｅｄＪｕｎｅ１６，１９９５...     

Effect of magnetic fields on viscous liquid column with finite length in a vertical straight tube

ＥＦＦＥＣＴＯＦＭＡＧＮＥＴＩＣＦＩＥＬＤＳＯＮＶＩＳＣＯＵＳＬＩＱＵＩＤＣＯＬＵＭＮＷＩＴＨＦＩＮＩＴＥＬＥＮＧＴＨＩＮＡＶＥＲＴＩＣＡＬＳＴＲＡＩＧＨＴＴＵＢＥＷｅｎＧｏｎｇ－ｂｉ（温功碧）;ＳｕｎＫｅ－ｌｉ（孙克利）（ＤｅｐａｒｔｍｅｎｔｏｆＭ...     

LARGE DEFLECTION PROBLEM OF THIN ORTHOTROPIC CIRCULAR PLATE ON ELASTIC FOUNDATION WITH VARIABLE THICKNESS UNDER UNIFORM PRESSURE

ＬＡＲＧＥＤＥＦＬＥＣＴＩＯＮＰＲＯＢＬＥＭＯＦＴＨＩＮＯＲＴＨＯＴＲＯＰＩＣＣＩＲＣＵＬＡＲＰＬＡＴＥＯＮＥＬＡＳＴＩＣＦＯＵＮＤＡＴＩＯＮＷＩＴＨＶＡＲＩＡＢＬＥＴＨＩＣＫＮＥＳＳＵＮＤＥＲＵＮＩＦＯＲＭＰＲＥＳＳＵＲＥ（王嘉新）（刘杰）ＬＡＲＧ...     

ELASTIC PULSE BUCKLING OF CYLINDRICAL SHELLS UNDER RADIAL IMPULSIVE LOADING

ＥＬＡＳＴＩＣＰＵＬＳＥＢＵＣＫＬＩＮＧＯＦＣＹＬＩＮＤＲＩＣＡＬＳＨＥＬＬＳＵＮＤＥＲＲＡＤＩＡＬＩＭＰＵＬＳＩＶＥＬＯＡＤＩＮＧＨｕａｎｇＣｈｅｎｇｙｉ（黄承义）ＬｉｕＴｕｇｕａｎｇ（刘土光）ＺｈｅｎｇＪｉｊｉａ（郑际嘉）（Ｄｅｐａｒｔｍｅｎｔｏ...     

A UNIFORMLY CONVERGENT DIFFERENCE SCHEME FOR THE SINGULAR PERTURBATION PROBLEM OF A HIGH ORDER ELLIPTIC DIFFERENTIAL EQUATION

ＡＵＮＩＦＯＲＭＬＹＣＯＮＶＥＲＧＥＮＴＤＩＦＦＥＲＥＮＣＥＳＣＨＥＭＥＦＯＲＴＨＥＳＩＮＧＵＬＡＲＰＥＲＴＵＲＢＡＴＩＯＮＰＲＯＢＬＥＭＯＦＡＨＩＧＨＯＲＤＥＲＥＬＬＩＰＴＩＣＤＩＦＦＥＲＥＮＴＩＡＬＥＱＵＡＴＩＯＮ（刘国庆）（苏煜城）ＡＵＮＩＦＯ...     

Stability of two-layer fluid flow

The problem of two-layer convective flow of viscous incompressible fluids in a horizontal channel with solid walls in the presence of evaporation is considered in the Oberbeck–Boussinesq approximation assuming that the interface is an undeformable thermocapillary surface and taking into account the Dufour effect in the upper layer which is a mixture of gas and liquid vapor. The effects of longitudinal temperature gradients at the boundaries of the channel and the thicknesses of the layer on the flow pattern and the evaporation rate are studied under conditions of specified gas flow and the absence of vapor flow on the upper boundary of the channel. It is shown that the long-wavelength asymptotics for the decrement is determined from the flow characteristics, the longwavelength perturbations occurring in the system decay monotonically, and the thermal instability mechanism is not potentially the most dangerous.     

Rarefied flow in a channel and a periodic system of channels

the steady two-dimensional isothermal rarefied flow in a channel formed by two parallel flat plates of finite length is studied on the basis of the numerical solution of a linearized kinetic problem. The channel may either be isolated or constitute a cell of a periodic cascade consisting of zero-thickness plates arranged one above the other. As the channel length increases, the flow in it approaches the asymptotic one-dimensional Poiseuille flow. It is shown that the asymptotic dependence of the gas flow rate on the low Knudsen number corresponding to an infinitely long channel is already attained for a channel of length equal to several channel widths, if the flow rate is referred to the pressure gradient at the middle of the channel rather than to the mean pressure difference at the channel ends. The effect of the boundary conditions imposed on the channel entrance is investigated. Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 3, pp. 166–175, May–June, 2000. The study was carried out with the support of the Russian Foundation for Basic Research (project No. 98-01-00443).     

Finite element‐fictitious boundary methods (FEM‐FBM) for 3D particulate flow

In this paper we discuss numerical simulation techniques using a finite element approach in combination with the fictitious boundary method (FBM) for rigid particulate flow configurations in 3D. The flow is computed with a multigrid finite element solver (FEATFLOW), the solid particles are allowed to move freely through the computational mesh which can be static or adaptively aligned by a grid deformation method allowing structured as well as unstructured meshes. We explain the details of how we can use the FBM to simulate flows with complex geometries that are hard to describe analytically. Stationary and time‐dependent numerical examples, demonstrating the use of such geometries are provided. Our numerical results include well‐known benchmark configurations showing that the method can accurately and efficiently handle prototypical particulate flow situations in 3D with particles of different shape and size. Copyright © 2011 John Wiley & Sons, Ltd.     

Turbulent natural convection flow in a vertical channel with anti-symmetric heating

This paper presents the fluid flow characteristics of natural convection flow in an anti-symmetrically heated parallel-plate vertical channel using the Particle Image Velocimetry (PIV) system. The channel walls were subjected to uniform temperature conditions, with one wall heated above ambient and the opposing wall maintained below ambient temperature. Velocity measurements were conducted at three different sections on the horizontal plane to validate two-dimensionality of the flow and at three different heights in the vertical plane to establish vertical mean velocity profiles. The results indicate that the flow recirculation in the channel exhibits a similar character to that of a closed cavity and the induced flow rate is much lower than the one for a channel with both walls heated. A correlation for the dimensionless flow rate is developed.     

In situ flow visualization of capillary flow of concentrated alumina suspensions

A new approach was taken to understand the flow behavior of concentrated particle suspensions in pressure-driven capillary flow. The flow of concentrated alumina suspensions in a slit channel was visualized and quantitatively analyzed with modified capillary rheometer. The suspensions showed complex flow behaviors; unique solid–liquid transition and shear banding. At low flow rates, 55 vol% alumina suspension showed a unique transient flow behavior; there was no flow at first and continuous change of flow profile was observed with time. At low shear rates in particular, the suspensions exhibited shear-banded flow profile which could be divided into three regions: the region with low flow rate near the wall, the region with rapid increase of flow velocity to maximum, and the region of velocity plateau. Based on both flow visualization and measurement of shear stress, it was found that the shear-banded flow profile in pressure-driven slit channel flow was strongly correlated with shear stress. The banding in pressure-driven flow was different from that in Couette flow. The banding of concentrated alumina suspensions was unique in that sluggish velocity profile was pronounced and two inflection points in velocity profile was exhibited. In this study, shear banding of concentrated alumina suspensions in slit channel flow was visualized and quantitatively analyzed. We expect that this approach can be an effective method to understand the flow behavior of particulate suspensions in the pressure-driven flow which is typical in industrial processing.     

Pressure effects on electroosmotic flow of power-law fluids in rectangular microchannels

In this paper, the fully developed electroosmotic flow of power-law fluids in rectangular microchannels in the presence of pressure gradient is analyzed. The electrical potential and momentum equations are numerically solved through a finite difference procedure for a non-uniform grid. A complete parametric study reveals that the pressure effects are more pronounced at higher values of the channel aspect ratio and smaller values of the flow behavior index. The Poiseuille number is found to be an increasing function of the channel aspect ratio for pressure assisted flow and a decreasing function of this parameter for pressure opposed flow. It is also observed that the Poiseuille number is increased by increasing the zeta potential. Furthermore, the results show that an increase in the flow behavior index results in a lower flow rate ratio, defined to be the ratio of the flow rate to that of a Newtonian fluid at the same conditions. Moreover, whereas the flow rate ratio in the presence of an opposed pressure gradient is smaller than that of a favorable pressure force for shear thinnings, the opposite is true for shear-thickening fluids.     

Effect of wall conductances on convective magnetohydrodynamic channel flow

Summary The problem of convective magnetohydrodynamic channel flow in a vertical channel subjected simultaneously to an axial temperature gradient and a pressure gradient is examined when the thermal and the electrical conductance of the channel walls are arbitrary. The effects of wall conductances on the flow rate and heat transfer are found and discussed. When the vertical temperature gradient is negative, which is the case of heating from below, there exists a critical Rayleigh number at which the fluid becomes unstable. The critical Rayleigh number is also found as a function of the wall conductances.On leave from the State University of New York at Buffalo.     

Linear stability analysis of flow in a periodically grooved channel

We have conducted the linear stability analysis of flow in a channel with periodically grooved parts by using the spectral element method. The channel is composed of parallel plates with rectangular grooves on one side in a streamwise direction. The flow field is assumed to be two‐dimensional and fully developed. At a relatively small Reynolds number, the flow is in a steady‐state, whereas a self‐sustained oscillatory flow occurs at a critical Reynolds number as a result of Hopf bifurcation due to an oscillatory instability mode. In order to evaluate the critical Reynolds number, the linear stability theory is applied to the complex laminar flow in the periodically grooved channel by constituting the generalized eigenvalue problem of matrix form using a penalty‐function method. The critical Reynolds number can be determined by the sign of a linear growth rate of the eigenvalues. It is found that the bifurcation occurs due to the oscillatory instability mode which has a period two times as long as the channel period. Copyright © 2003 John Wiley & Sons, Ltd.     

Ethanol–CO2 two-phase flow in diverging and converging microchannels

The present study investigates experimentally two-phase flow patterns and pressure drop of ethanol and CO₂ in a converging or diverging rectangular microchannel. The two-phase flow pattern visualization is made possible using a high speed video camera. The increased superficial gas velocity due to the acceleration effect and the large pressure drop in a converging channel may result in the elongation of bubbles in slug flow, while the decreased superficial velocity owing to the deceleration effect and the possible pressure rise in the diverging channel may cause shortening of bubbles in slug flow significantly. For both types of channel, the collision and merger of two consecutive bubbles may take place and result in necking of bubbles. Two-phase flow pressure drop in the converging microchannel increases approximately linearly with the increasing liquid or gas flow rate with the frictional pressure drop being the major contributor to the channel pressure drop. In the diverging microchannel, the deceleration effect results in the pressure rise and counteracts the frictional pressure drop. Consequently, for low liquid flow rates the channel pressure drop increases only slightly with the gas flow rate while it is low and a reversed trend appears while it is high. For high liquid flow rates the effect of increasing gas flow rate on channel pressure drop is much more significant; a more significant reverse trend of the effect of gas flow rate is present in the region of high gas flow rates. The two-phase frictional multiplier in the converging or diverging microchannel is quite insensitive to the liquid flow rate and can be fitted very well within ±15% based on the Lockhart–Martinelli equation with a modified Chisholm parameter for the diverging microchannel and together with a modified coefficient for the X⁻² term for the converging microchannel.     

Fluid flow and heat transfer in a two-dimensional wavy channel

A numerical study is presented for the laminar fully developed flow and heat transfer in a two-dimensional wavy channel. The effects of the geometry, Reynolds and Prandtl number on the flow field and heat transfer are investigated. The channel is characterized by a wavy wall, heated at uniform heat flux, and an opposite wall, being plane and adiabatic. The extent of the wall waviness and the distance between the channel walls are found to significantly affect the streamlines contours as well as the heat transfer coefficients. Comparisons with the straight channel, in the same flow rate and heat transfer conditions, have been performed. Pressure drop of the wavy channel is found to be always larger than the value characteristic of a straight channel, while heat transfer performance decreases or increases depending on the values of the parameters (geometry, Reynolds and Prandtl numbers).