Vortex Instability of Free Convection Flow Over Horizontal and Inclined Surfaces


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.


Mechanical and Aerospace Engineering

Keywords and Phrases

Flow (Dynamics); Natural Convection; Vortices; Heat Transfer; Stress; Waves; Shear (Mechanics); Stability

Document Type

Article - Journal

Document Version


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© 1982 American Society of Mechanical Engineers (ASME), All rights reserved.