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1

Numerical analysis of a velocity distribution of a fluid flow inside a reversing chamber

Judt W., Bartoszewicz J.

Journal of KONES

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2018

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Vol. 25, No. 3

247--251

EN

Axisymmetric stream, which is directed into an obstacle, is an important type of a fluid flow for technical applications in a large amount of thermal and flow devices. The article presents a case wherein stream of a fluid is directed into a flat surface and changes the direction of a flow by an angle equal to 90°. After that, the free stream is changing a character of a flow into impinging stream. The article presents a methodology of numerical calculations preparation in ANSYS Fluent environment for a velocity distribution of an airflow inside a reversing chamber. Numerical calculations were prepared for a three-dimensional model as an unsteady simulation with Delayed Detached Eddy Simulation model of turbulence. A stream of an air, which was analysed inside a reversing chamber, was not initially swirled. Obtained results of realized calculations were compared with experimental analysis and numerical calculations, which was realized in a different environment by co-author. Model of reversing chamber, which was implemented into numerical analysis has the same dimensions as used in experimental research. Obtained results show areas of intense flow turbulence inside reversing chamber. Prepared numerical calculations agreed with experimental results of research and allowed to designate areas of stream core and impinging stream inside modelled chamber.

2

Entropy generation on mhd flow of Powell-Eyring fluid between radially stretching rotating disk with diffusion-thermo and thermo-diffusion effects

Khan N. A., Aziz S., Ullah S.

Acta Mechanica et Automatica

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2017

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Vol. 11, no. 1

20--32

EN

An investigation is performed for an alyzing the effect of entropy generation on the steady, laminar, axisymmetric flow of an incompressible Powell-Eyring fluid. The flow is considered in the presence of vertically applied magnetic field between radially stretching rotating disks. The Energy and concentration equation is taking into account to investigate the heat dissipation, Soret, Dufour and Joule heating effects. To describe the considered flow non-dimensionalized equations, an exact similarity function is used to reduce a set of the partial differential equation into a system of non-linear coupled ordinary differential equation with the associated boundary conditions. Using homotopy analysis method (HAM), an analytic solution for velocity, temperature and concentration profiles are obtained over the entire range of the imperative parameters. The velocity components, concentration and temperature field are used to determine the entropy generation. Plots illustrate important results on the effect of physical flow parameters. Results obtained by means of HAM are then compared with the results obtained by using optimized homotopy analysis method (OHAM). They are in very good agreement.

3

Wyznaczanie przepływów Stokesa w przewodach profilowanych metodą elementów brzegowych

Teleszewski T. J., Sorko S. A.

Symulacja w Badaniach i Rozwoju

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2013

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Vol. 4, nr 1

41--50

PL

W opracowaniu przedstawiono zastosowanie metody elementów brzegowych (MEB) do wyznaczania przepływów Stokesa w profilowanych przewodach i kołowym przekroju poprzecznym metodą elementów brzegowych. W celu walidacji metody elementów brzegowych porównano rozwiązania numeryczne zrealizowane metodą elementów brzegowych z rozwiązaniem analitycznym i rezultatami eksperymentalnymi. W prezentowanej pracy przedstawiono graficzne rezultaty obliczeń dla wybranych przykładów, dla których nie są znane rozwiązania analityczne.

EN

The aim of the article is to present a simulation of steady Stokes flow in a circular pipe with changing axisymmetric of radius of the tube using the Boundary Element Method (BEM). Results of this method were compared with experiment result of Taneda and analytical solution. Examples of BEM solution Stokes flow through nozzle, deep caving and rounded caving are also presented. The software was written for a PC computer.

4

Vishwakarama J. P., Pathak P.

Journal of Theoretical and Applied Mechanics

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2012

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Vol. 50 nr 2

563-575

EN

Similarity solutions are obtained for an adiabatic flow behind a cylindrical shock wave propagating in a rotational axisymmetric flow of a perfect gas, in which initial velocity and density are functions of the distance from the axis of symmetry. The initial medium is considered to have a variable azimuthal velocity component in addition to the variable axial velocity. Initial velocities and density are assumed to obey power laws. Distributions of the fluid velocities, density, pressure and vorticity components are obtained in the flow-field behind the shock front. Effects of variable initial velocities and density and the variation of the shock-Mach number are investigated.

PL

W pracy przedstawiono rozwiązania automorficzne otrzymane dla adiabatycznego przepływu czynnika za cylindryczną fala uderzeniową rozchodzącą się w rotacyjnym, osiowo-symetrycznym opływie gazu doskonałego, którego prędkość początkowa oraz gęstość są funkcjami odległości od osi symetrii. W stanie początkowym, analizowany czynnik posiada oprócz zmiennej składowej osiowej prędkości dodatkowo zmienną składową azymutalną. Założono, że prędkości początkowe i gęstość opisują funkcje potęgowe. Rozkłady prędkości płynu, gęstość, ciśnienie oraz składowe wirowości otrzymano w polu przepływu za frontem fali uderzeniowej. Zbadano także wpływ prędkości początkowych oraz gęstości na zmiany wartości liczby Macha.

5

Vishwakarma J. P., Pathak P.

International Journal of Applied Mechanics and Engineering

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2012

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Vol. 17, no. 2

603-619

EN

Similarity solutions are obtained for an adiabatic flow behind a magnetogasdynamic cylindrical shock wave propagating in a rotational axisymmetric flow of a perfect gas in the presence of a variable azimuthal magnetic field. The initial medium is considered to have a variable density and a variable azimuthal velocity component in addition to a variable axial velocity. Initial velocities, density and the magnetic field are assumed to obey power laws. Distributions of the fluid velocities, density, pressure, magnetic field and vorticity components are obtained in the flow-field behind the shock front. Effects of an increase in the value of the index for variation of an ambient azimuthal magnetic field, in the value of the index for ambient density and in the strength of the initial magnetic field are obtained. It is found that the presence of the magnetic field has a decaying effect on the shock wave.

6

Steady axisymmetric flow and heat transfer of micropolar fluid over a vertical permeable slender cylinder in the presence of thermal radiation

Mansour M. A., Mohamed R. A., Abd Elaziz M. M., Ahmed S. E.

International Journal of Applied Mechanics and Engineering

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2010

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Vol. 15, no 4

1185-1203

EN

The effects of thermal radiation and suction/blowing on an axisymmetric flow and heat transfer of a micropolar fluid over a vertical slender cylinder are analyzed. The partial differential equations governing the flow and heat transfer have been transformed to ordinary differential equations by using similarity transformations which are then solved numerically. The numerical results are validated by favorable comparisons with previously published results. The cases of buoyancy-assisted flow, pure mixed convection, buoyancy opposed flow, permeable cylinder, impermeable cylinder, Newtonian fluids and non-Newtonian fluids as well as the case which represents concentrated particle flow in which the microelements close to the wall surface are unable to rotate and the case which indicates vanishing of an antisymmetric part of the stress tensor are considered. A parametric study of the governing parameters, namely the buoyancy parameter, suction/injection parameter, radiation parameter, vortex viscosity parameter, curvature parameter and microgyration boundary conditions parameter on the linear velocity, angular velocity and temperature as well as the wall stress, wall couple stress and the rate of heat transfer is conducted. A selected set of numerical results is presented graphically and discussed.

7

Flow characteristics in a vascular tube with an overIapping constriction

Pramanik S., Mukhopadhyay S., Layek G. C., Samad S. A.

International Journal of Applied Mechanics and Engineering

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2007

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Vol. 12, no 1

153-167

EN

A numerical solution to the unsteady blood flow in the neighbourhood of an overlapping constriction is obtained under laminar flow conditions. Blood is modelled as a viscous, incompressible and of Newtonian type fluid. A finite-difference staggered grid has been used to solve the unsteady incompressible Navier-Stokes equations in cylindrical polar co-ordinates under the axi-symmetric conditions. A co-ordinate transformation has been employed to map the constricted tube into a straight tube. The effect of flow characteristics in this type of constriction and its consequences in arterial diseases are investigated. Flow features such as velocity, pressure and wall shear stress distributions are presented graphically. The secondary separation has been noted in the downstream of the overlapping constriction when the Reynolds number of the flow is about 205.

8

Thermal dispersion effects on non-Darcy axisymmetric free convection in a porous medium saturated with a non-Newtonian fluid

El-Amin M. F.

International Journal of Applied Mechanics and Engineering

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2005

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Vol. 10, no 1

77-86

EN

A boundary layer analysis is presented to study the effects of thermal dispersion of a non-Newtonian fluid on non-Darcy axisymmetric free convection over a horizontal surface embedded in a porous medium. The Ostwald-de-Waele power-law model is used to characterize the non-Newtonian fluid behavior. The thermal diffusivity coefficient has been assumed to be the sum of the molecular diffusivity and the dynamic diffusivity due to mechanical dispersion. Similarity solutions are obtained when the surface temperature varies as the square root of the radial distance (i.e., the prescribed temperature PT) or when heat flux is constant (i.e., the prescribed heat flux PHF). The effects of the dispersion and non-Darcy parameters as well as the power-law index n on the velocity, temperature, the Nusselt number and the boundary layer thickness are shown on graphs. The numerical values of the rate of heat transfer through the boundary layer in terms of the Nusselt number are entered in a table.

9

Viscous-inviscid interactions for surface-cooled axisymmetric boundary-layer flows

Elliott J. W., Strange M. E.

Applied Mechanics and Engineering

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2000

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Vol. 5, no 4

923-957

EN

A theoretical, high Reynolds number, investigation into the combined influence of surface cooling and curvature on the stability and transition properties of a compressible axisymmetric boundary-layer is presented. Here we consider the boundary-layer flow along a semi-infinite circular cylinder where the temperature of the cylinder surface is kept significantly below the free-stream temperature and the cylinder radius is comparable with the boundary-layer thickness. Here we concentrate on linear, viscous-inviscid interactive Tollmien-Schlichting modes, rather than the inviscid, inflectional kind.

10

Thermal dispersion effects on non-Darcy axisymmetric free convection in a saturated porous medium with lateral mass transfer

Mansour M. A., El-Amin M. F.

Applied Mechanics and Engineering

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1999

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Vol. 4, no 4

727-737

EN

An analysis is presented to study the effects of thermal dispersion and lateral mass flux on non-Darcy axisymmetric free convection on permeable horizontal surfaces in a fluid saturated porous medium. The thermal diffusivity coefficient has been assumed to be the sum of the molecular diffusivity and the dynamic diffusivity due to mechanical dispersion. Similarity solutions are obtained when the surface temperature varies as the square root of the radial distance or when heat flux is constant. The effects of the dispersion, lateral mass flux and non-Darcy parameters on the velocity and temperature are shown on graphs. The numerical values of the rate of heat transfer as well as the total energy convected through the boundary layer are entered in tables.