Wyniki wyszukiwania - BazTech

1

Drag on a permeable sphere placed in a micropolar fluid with non-zero boundary condition for microrotations

Mishra V., Gupta B. R.

Journal of Applied Mathematics and Computational Mechanics

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2016

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Vol. 15, nr 3

97--109

EN

This paper concerns an analytical study of an infinite expanse of uniform flow of steady axisymmetric creeping flow of an incompressible micropolar fluid around the permeable sphere assuming a nonhomogeneous boundary condition for microrotation vector. It is assumed that microrotation vector is proportional to the rotation rate of velocity vector. The stream function solutions for the flow fields are obtained in the terms of modified Bessel’s functions and Gegenbauer functions. Continuity of normal velocity, no-slip condition, non-zero microrotation vector on the sphere, uniform velocity at infinity are the different boundary conditions used to determine the flow fields explicitly. The microrotation component, pressure field, bounds of permeability parameter and drag force experienced by the permeable sphere are calculated. Dependence of the drag force on different fluid parameters is presented graphically and discussed. It is found that drag force decreases with increasing spin parameter. Several cases of interest are deduced from the present analysis.

2

Scattering of internal waves by vertical barrier in a channel of stratified fluid

Dolai P.

International Journal of Applied Mechanics and Engineering

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2015

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Vol. 20, no. 3

471--485

EN

The problem of two dimensional internal wave scattering by a vertical barrier in the form of a submerged plate, or a thin wall with a gap in an exponentially stratified fluid of uniform finite depth bounded by a rigid plane at the top, is considered in this paper. Assuming linear theory and the Boussinesq approximation, the problem is formulated in terms of the stream function. In the regions of the two sides of the vertical barrier, the scattered stream function is represented by appropriate eigen function expansions. By the use of appropriate conditions on the barrier and the gap, a dual series relation involving the unknown elements of the scattering matrix is produced. By defining a function with these unknown elements as its Fourier sine expansion series, it is found that this function satisfies a Carleman type integral equation on the barrier whose solution is immediate. The elements of the scattering matrix are then obtained analytically as well as numerically corresponding to any mode of the incident internal wave train for each barrier configuration. A comparison with earlier results available in the literature shows good agreement. To visualize the effect of the barrier on the fluid motion, the stream lines for an incident internal wave train at the lowest mode are plotted.

3

Mathematical Modeling and Numerical Analysis of Nonstationary Plane-Parallel Flows of Viscous Incompressible Fluid by R-Functions and Galerkin Method

Artyukh A., Sidorov M.

ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes

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2014

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Vol. 3, No 3

3-11

EN

This paper is dedicated to nonstationary plane-parallel flows of viscous incompressible fluid in finite simply connected domains. Theorem of the solution uniqueness is presented. The method of successive approximation, the Galerkin method and the R-functions method are used to obtain the numerical solution, which was tested on the problem with known solution.

4

Image Segmentation Using Streamlines Analogy

Youssef B. A.

Machine Graphics and Vision

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2010

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Vol. 19, No. 1

19-31

EN

This paper presents a novel method for digital image segmentation based on the analogy between streamlines in fluid dynamics and isophote lines in digital images. The segmentation problem is reformulated so that the image intensity corresponds to the stream function for a two-dimensional, incompressible flow, and image intensity gradients are represented as the fluid velocity vector. Segmentation is effected by computing the streamlines by solving a coupled system of ordinary differential equations using a fourth-order Runge-Kutta method. Selection of the initial starting point for segmentation is based on color homogeneity in terms of local color gradient, and on variance. The effectiveness of the developed segmentation method is demonstrated through a number of case studies, ranging from gray level to colored images.

5

Zastosowanie funkcji prądu w opisie kinematyki plastycznego płynięcia w procesie wyciskania kształtowników

Pawłowska B., Śliwa R. E.

Rudy i Metale Nieżelazne

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2007

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R. 52, nr 11

812-819

PL

Przedstawiono wyniki badań dotyczących opisu kinematyki plastycznego płynięcia i niejednorodności plastycznej materiału podczas wyciskania wyrobów o różnym kształcie przekroju poprzecznego na przykładzie przekroju kołowego oraz prostokątnego. Przedstawione doświadczalne przebiegi funkcji prądu stanowią bezpośrednią praktyczną wskazówkę do teoretycznego opisu procesu wyciskania. Teoretycznie określone linie prądu pozostają w dużej zgodności z doświadczalnymi liniami płynięcia. Mogą one służyć do konstruowania nowych schematów plastycznego płynięcia materiału w procesie wyciskania.

EN

The paper presents results of the investigations included description of kinematics of material flow and inhomogeneity of materials flow during extrusion of profiles about complex geometry of the cross-section. It has been shown that experimental courses of stream function present direct practical hand for theoretical description of extrusion process. Theoretical stream line stay in large agreement with experimental flow lines. They can be as for constructing new scheme of the metal flow in extrusion process.

6

Studium konwekcyjnego ruchu powietrza nad powierzchnią ogrzewanej płyty metodą symulacji numerycznej

Trzciński P.

Inżynieria i Aparatura Chemiczna

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2006

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Nr 6s

243-244

EN

Elaboration of a numeric model describing convectional heat transfer in the system consisting of warmed plate source and enclosing air was the aim of this work. The two-dimensional temperature field, vorticity, stream function and velocity distribution were presented. Convectional movement was modelled using the MRS method in the MATLAB environment programme. Key words: convection, MRS, stream function, vorticity

7

Numerical resolution of incompressible navier-stokes equations in the stream function formulation

Kosma Z.

Inżynieria Chemiczna i Procesowa

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2006

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T. 27, z. 3/1

737-760

EN

The method of lines is applied to simulate the motion of viscous incompressible fluid in a driven cavity and around an aerofoil at a large angle of attack. The numerical algorithms are based on the solution of an initial-boundary value problem for the full incompressible Navier-Stokes equations in the form of the fourth order equation for the stream function. Calculations for the cavity flow configuration have been obtained for Reynolds numbers ranging from 5000 to 30 000 on the non-uniform grids 100x100 and a uniform grid 150x150. Computations for the flow around the aerofoil have been performed at Reynolds numbers Re = or < 1000.

PL

Przedstawiono algorytmy numeryczne do symulacji płaskiego, niestacjonarnego ruchu cieczy lepkiej. Do rozwiązywania równań Naviera-Stokesa zastosowano metodę prostych, polegającą na sprowadzaniu zagadnień początkowo-brzegowych dla równania czwartego rzędu dla funkcji prądu do zagadnień początkowych dla układów równań różniczkowych zwyczajnych. Wykonano symulację ruchu cieczy lepkiej w kwadratowym zagłębieniu z jedną poruszającą się ścianką dla liczby Reynoldsa w zakresie 5000-30 000 na siatkach: nierównomiernej 100x100 i równomiernej 150x150 oraz symulację opływu profilu lotniczego nachylonego pod dużym kątem natarcia do napływającego strumienia w nieskończoności dla Re = lub < 1000.

8

Boundary layer MHD flow of a viscoelastic fluid over a porous quadratic stretching sheet

Khan S. K.

International Journal of Applied Mechanics and Engineering

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2005

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Vol. 10, no 2

267-279

EN

A mathematical analysis on the boundary layer MHD flow of a viscoelastic fluid over a porous stretching sheet has been presented in this paper. A typical choice of quadratic stretching of the boundary, which generates a quadratic part in velocity parallel to the boundary sheet and a linear mass flux part in the velocity normal to the stretching sheet, has been assumed. Streamline patterns and skin friction coefficients are discussed for various values of nondimensional physical parameters. The result of the analysis reveals that the combined effect of the non-dimensional viscoelastic parameter and Hartmann number is to increase significantly the values of skin friction coefficient, whereas, the combined effect of the nondimensional constant mass flux parameter and modified linear mass flux parameter is to reduce largely the values of skin friction coefficient. For positive values of the linear mass flux parameter the stream functions attain a positive slope away from the origin while they attain a negative slope everywhere for zero value. The limiting cases of our results yield the results of Andersson (1992) and Kumaran and Ramanaiah (1996).

9

Viscoelastic boundary layer MHD flow through a porous medium over a porous quadratic stretching sheet

Kumar Khan S., Sanjayanand E.

Archives of Mechanics

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2004

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Vol. 56, nr 3

191-204

EN

Boundary layer MHD flow of a viscoelastic fluid in a porous medium over a porous stretching sheet has been presented in this article. A typical choice of quadratic stretching of the boundary, having a quadratic part in velocity parallel to the boundary sheet and a linear mass flux in the velocity normal to the stretching sheet, constitutes the boundary conditions of the problem. The effect of various values of nondimensional physical parameters on streamline patterns and skin friction coefficient are discussed. Some of the important findings of the article are: (a) the flow is enhanced by the positive values of linear mass flux parameter and suppressed by the negative values of linear mass flux parameter; (b) the effect of permeability parameter is not significant when linear mass flux parameter takes zero or negative values; (c) the combined effect of reduction of the values of permeability parameter, Hartmann number and linear mass flux parameter is expected to reduce largely the values of skin friction coefficient.

10

Rozwiązywanie zagadnienia opływu profilu lotniczego cieczą lepką dla funkcji prądu

Kosma Z., Noga B.

Zeszyty Naukowe Katedry Mechaniki Stosowanej / Politechnika Śląska

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2003

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z. 20

232-237

PL

Przedstawione zostały własne algorytmy numeryczne, przeznaczone do obliczania płaskiego ruchu cieczy lepkiej wokół profilu lotniczego, nachylonego do kierunku napływu pod dużym kątem natarcia - oparte na rozwiązywaniu zagadnienia początkowo-brzegowego dla pełnych równań Naviera-Stokesa, sprowadzonych do równania czwartego rzędu dla funkcji prądu. Obliczenia zostały wykonane na równomiernej siatce 100 x 100 w obszarze kanonicznym dla dwóch liczb Reynoldsa: Re = 200, Re = 400. Jako warunki: początkowe i brzegowe na granicy zewnętrznej przyjęto rozwiązania dla opływu profilu cieczą doskonałą.

EN

The purpose of this paper is to simulate the plane motion of viscous incompressible fluid around an aerofoil at large angle of attack. The developed numerical algorithms are based on solving an initial-boundary value problem for the full incompressible Navier-Stokes equations, written in the form of the fourth-order equation for the stream function. Calculations have been made on the uniform grid 100 x 100 in a canonical domain at Reynolds numbers of Re = 200 and Re = 400. The initial and the outer boundary conditions used for the computation are the solutions of irrotational flow of ideal fluid.