Natural-Convection Flow Along a Vertical Complex Wavy Surface With Uniform Heat Flux

2007 ◽  
Vol 129 (10) ◽  
pp. 1403-1407 ◽  
Author(s):  
Mamun Molla ◽  
Anwar Hossain ◽  
Lun-Shin Yao
Keyword(s):  
Boundary Layer ◽  
Heat Flux ◽  
Natural Convection ◽  
Wavy Surface ◽  
Convection Flow ◽  
Convection Boundary Layer ◽  
Uniform Heat Flux ◽  
Fundamental Wave ◽  
Computational Domain ◽  
Uniform Heat

A natural-convection boundary layer along a vertical complex wavy surface with uniform heat flux has been investigated. The complex surface studied combines two sinusoidal functions, a fundamental wave and its first harmonic. Using a method of transformed coordinates, the boundary-layer equations are mapped into a regular and stationary computational domain. The transformed equations can then be solved straightforwardly by any number of numerical methods designed for regular and stationary geometries. In this paper, an implicit finite-difference method is used. The results were readily obtained on a personal computer. The numerical results demonstrate that the additional harmonic substantially alters the flow field and temperature distribution near the surface. The induced velocity normal to the y axis can substantially thicken the boundary layer, implying that its growth is not due solely to the momentum and thermal diffusion normal to the y axis along a wavy surface.

scholarly journals Heat and mass transfer effects on natural convection flow along a horizontal triangular wavy surface

2017 ◽  
Vol 21 (2) ◽  
pp. 977-987 ◽  
Author(s):  
Sadia Siddiqa ◽  
Anwar Hossain ◽  
A Aqsa
Keyword(s):  
Boundary Layer ◽  
Mass Transfer ◽  
Shear Stress ◽  
Natural Convection ◽  
Heat And Mass Transfer ◽  
Complex Geometry ◽  
Linear Equations ◽  
Wavy Surface ◽  
Convection Flow ◽  
Convection Boundary Layer

An analysis is carried out to thoroughly understand the characteristics of heat and mass transfer for the natural convection boundary layer flow along a triangular horizontal wavy surface. Combine buoyancy driven boundary layer equations for the flow are switched into convenient form via co-ordinate transformations. Full non-linear equations are integrated numerically for Pr = 0.051. Interesting results for the uneven surface are found which are expressed in the form of wall shear stress, rate of heat transfer and rate of mass transfer. Solutions are also visualized via streamlines, isotherms, and isolines for concentration. Computational results certify that, shear stress, temperature gradient and concentration gradient enhances as soon as the amplitude of the wavy surface, a, increases, but complex geometry do not allow to carry simulations for a > 1.5. This factor probably ensures that sinusoidal waveform is better than triangular waveform. <br><br><font color="red"><b> This article has been corrected. Link to the correction <u><a href="http://dx.doi.org/10.2298/TSCI170525126E">10.2298/TSCI170525126E</a><u></b></font>

A theoretical investigation of disturbance amplification in external laminar natural convection

1968 ◽  
Vol 34 (3) ◽  
pp. 551-564 ◽  
Author(s):  
R. P. Dring ◽  
B. Gebhart
Keyword(s):  
Boundary Layer ◽  
Heat Flux ◽  
Natural Convection ◽  
Amplitude Ratio ◽  
Low Frequency ◽  
Leading Edge ◽  
Convection Boundary Layer ◽  
Uniform Heat Flux ◽  
Laminar Natural Convection ◽  
Sommerfeld Equation

The nature of instability and disturbance amplification in the laminar natural convection boundary layer over a vertical flat surface with uniform heat flux has been theoretically investigated. The coupled Orr-Sommerfeld equation has been numerically integrated for a Prandtl number of 6·7, with the boundary condition that the disturbance heat flux be zero at the surface. The spatial amplification characteristics of disturbances convected downstream were analyzed, and constant amplification rate contours were determined. The relative amplification has been calculated from these contours and is presented in the form of amplitude ratio contours. An important feature of these results is that the low frequency disturbances, which become unstable first, amplify very slowly and also have wavelengths which are much longer than the distance to the leading edge. The higher frequency, shorter wavelength, disturbances amplify much faster and are, therefore, presumed to be the dominant ones in stability considerations. The nature of the velocity and temperature amplitudes and phase profiles across the boundary layer has also been examined.

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