Vortex Instability of Free Convection Flow Over Horizontal and Inclined Surfaces

1982 ◽  
Vol 104 (4) ◽  
pp. 637-643 ◽  
Author(s):  
T. S. Chen ◽  
K. L. Tzuoo
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
Surface Heat ◽  
Convection Flow ◽  
Neutral Stability ◽  
Free Convection Flow ◽  
Vortex Instability ◽  
Surface Heat Transfer ◽  
Wide Range ◽  
Prandtl Numbers

The vortex instability characteristics of laminar free convection flow over horizontal and inclined isothermal surfaces are studied analytically by linear theory. As a prelude to the analysis, the effects of the angle of inclination on the main flow and thermal fields are re-examined by a new approach. Numerical results are presented for wall shear stress, surface heat transfer, neutral stability curve, and critical Grashof number for Prandtl numbers of 0.7 and 7 over a wide range of angles of inclination, φ, from the horizontal. It is found that as the angle of inclination increases the rate of surface heat transfer increases, whereas the susceptibility of the flow to the vortex mode of instability decreases. The present study provides new vortex instability results for small angles of inclination (φ≤30 deg) and more accurate results for large angles of inclination (φ ≥ 30 deg) than previous studies. The present results are also compared with available wave instability results.

Local Nonsimilarity Solution of Free Convection Flow and Heat Transfer from an Inclined Isothermal Plate

1979 ◽  
Vol 101 (4) ◽  
pp. 642-647 ◽  
Author(s):  
M. M. Hasan ◽  
R. Eichhorn
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Free Convection ◽  
Prandtl Number ◽  
Numerical Solutions ◽  
Convection Flow ◽  
Appreciable Effect ◽  
Free Convection Flow ◽  
Flow And Heat Transfer ◽  
Prandtl Numbers

The effect of the angle of inclination on free convection flow and heat transfer from an isothermal surface is analyzed by the local nonsimilarity method of solution. An inclination parameter ξ as obtained from the analysis is tan γ/4 (Grx/4)1/4, where γ is the angle of inclination measured from the vertical and Grx is the local Grashof number, based on the component of the gravity vector along the surface. Numerical solutions of the equations are obtained for Prandtl numbers of 0.1, 0.7, 6 and 275. Results show an appreciable effect of ξ on the velocity field, and practically none on the temperature field, except for very large angles of inclination from the vertical or for very small values of the Prandtl number. In the limiting case of very large Prandtl number, ξ has no effect either on the velocity or the temperature field.

scholarly journals Free convection flow of power law fluid in a vertical cylinder of finite height

1995 ◽  
Vol 17 (2) ◽  
pp. 34-39
Author(s):  
Nguyen Van Que
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
Power Law ◽  
Average Velocity ◽  
Vertical Cylinder ◽  
Convection Flow ◽  
Power Law Fluid ◽  
Free Convection Flow ◽  
Finite Height ◽  
Good Agreement

A numerical solution has been presented for free convection flow of power law fluid in a vertical cylinder of finite height. The average velocity along the channel and the heat transfer have been calculated. Graphs of velocities and temperature are shown. The results show good agreement with analytic one in the asymptotic case.

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