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1

Viscoelastic liquid flow and heat transfer over a stretching sheet in porous medium with nonuniform heat source

Abel M. S., Nandeppanavar M. M., Malkhed M. B.

International Journal of Applied Mechanics and Engineering

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2009

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Vol. 14, no 1

5-19

EN

This paper presents an analytical study of a steady boundary layer visco-elastic liquid flow over a non-isothermal stretching sheet embedded in a porous medium in the presence of non-uniform heat generation / absorption. The stretching of the sheet is assumed to be proportional to the perpendicular distance from the slit. Two different temperature conditions are considered, viz., (i) the sheet with a prescribed surface temperature (PST) and (ii) the sheet with a prescribed wall heat flux (PHF). The non-linear boundary layer equations for momentum are converted into non-linear ordinary differential equations by means of a similarity transformation and the same is solved exactly. The heat transport equation with variable coefficients is transformed into a confluent hypergeometric differential equation and solved analytically. The effect of various parameters on the temperature distribution is presented graphically. The numerical calculations have been carried out for various values of non-dimensional physical parameters, the results tabulated the results and discussed.

2

A theoretical study of the effect of a non-uniform heat source on heat transfer in a viscoelastic liquid flow over a stretching sheet

Nandeppanavar M. M., Abel M. S., Malipatil S.

International Journal of Applied Mechanics and Engineering

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2009

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Vol. 14, no 4

1039-1052

EN

A theoretical study of heat transfer in a visco-elastic liquid flow due to a stretching sheet in the presence of non-uniform heat generation / absorption is investigated. The stretching of the sheet is assumed to be proportional to the perpendicular distance from the slit. Two different temperature conditions are studied, viz., (i) the sheet with the prescribed surface temperature (PST) and (ii) the sheet with the prescribed wall heat flux (PHF). The non-linear boundary layer equations for momentum are converted into non-linear ordinary differential equations by means of a similarity transformation and the same is solved exactly. The heat transport equation with variable coefficients is transformed into a confluent hypergeometric differential equation and solved analytically. The effect of various parameters on the temperature distribution is presented graphically. Present results are compared with the existing theoretical data and found in good agreement with these results. The results have technological applications in liquid based systems involving stretchable materials.

3

Kawitacja w płynach lepkich i lepkosprężystych

Sitka A., Redzicki R.

Inżynieria Chemiczna i Procesowa

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2006

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T. 27, z. 3/1

847-857

PL

Przedstawiono równania i numeryczne rozwiązania oscylacji pęcherzyka kawitacyjnego w płynie nieniutonowskim lepkim i lepkosprężystym. Właściwości lepkie płynu opisano modelem potęgowym, a właściwoości lepkosprężyste modelem OWF (Oldroyda-Waltersa-Fridricksona). Uzyskane z obliczeń numerycznych charakterystyki oscylacji pojedynczego pęcherzyka kawitacyjnego różnią się dla cieczy niutonowskiej i nieniutonowskiej. Z przeprowadzonej analizy numerycznej wynika, że lepkość i sprężystość płynu w znaczny sposób ograniczają zjawisko kawitacji. Wskazują na to uzyskane charakterystyki zależności oscylacji prędkości i ciśnienia, wykazujące zmniejszenie amplitudy drgań pęcherzyka wraz ze wzrostem lepkości i sprężystości płynu.

EN

The paper presents the equations and numerical solutions of oscillation of the bubble cavitation in the non-Newtonian viscous fluid and viscoelastic fluid. The properties of viscous liquid were described by the involution model and the viscoelastic properties by the OWF (Oldroyd-Walters-Fridrickson) model. The characteristics of oscillation of a single bubble cavitation obtained from the numerical calculations are different for the Newtonian and non-Newtonian liquids. From the numerical analysis it follows that the viscosity and elasticity of fluid significantly limit the cavitation effect. The characteristics of velocity and pressure oscillation show the reduction of vibration amplitude of a bubble along with the increasing viscosity and elasticity of fluid.

4

On the possibility of overstable motion of a rotating viscoelastic fluid layer heated from below under the effect of magnetic field with one relaxation time

Othman M. I. A.

Mechanics and Mechanical Engineering

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2004

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Vol. 7, nr 1

41-51

EN

The convective stability of a horizontal layer of viscoelastic conducting liquid (Walters' liquid B') heated from below and rotating about a vertical axis in the presence of a magnetic field and thermal relaxation has been investigated. Linear stability theory and normal mode analysis are used to derive an eigenvalue system of eighth order, and an exact eigenvalue equation for a neutral instability is obtained. Critical Rayleigh numbers and wave numbers for the onset of instability are presented graphically as functions of Taylor number for various values of the Chandrasekhar number and the relaxation time at a Prandtl number Pr = l.