Variable Permeability Effect on Vortex Instability of Free Convection Flow Over Inclined Heated Surfaces in Porous Media

• Autorzy: Ibrahim F. S.
• Języki publikacji: EN

Abstrakty

EN

A linear stability analysis is performed for the study of the onset of vortex instability in free convection flow over an inclined heated surface in a porous medium, where the wall temperature is a power function of the distance from the origin. The variation of permeability in the vicinity of the solid boundary is approximated by an exponential function. The variation rate itself depends slowly on the streamwise coordinate, such as to allow the problem to possess a set of solutions, invariant under a group of transformations. Velocity and temperaturę profiles as well as local Nusselt number for the base flow are presented for the uniform permeability UP and variable permeability VP cases. The resulting variable coefficient eigenvalue problem is solved numerically. The critical parameter Ra*xtan2 ø and the critical wave number k* are computed for different prescribed wall temperature distribution of the inclined surface for both UP and VP cases. It is found that the larger the inclination angle with respect to the vertical, the morę susceptible is the flow for the vortex mode of disturbances; and in the limit of zero inclination angle (i.e vertical heated plate) the flow is stable for this form of disturbances. Also, it is found that the variable permeability effect tends to increase the heat transfer rate and destabilize the flow to the vortex mode of disturbance.

Słowa kluczowe

EN

free convection; vortex instability; inclined surface; porous media; variable permeability; variable porosity

PL

konwencja swobodna; niestabilność wiru; materiały porowate

• Wydawca: Wydawnictwo Politechniki Łódzkiej
• Czasopismo: Mechanics and Mechanical Engineering
• Rocznik: 2009
• Tom: Vol. 13, nr 2
• Strony: 55--67
• Opis fizyczny: Bibliogr. 19 poz.

Twórcy

autor

Ibrahim F. S.

• Department of mathematics Faculty of Science, Assiut University Assiut, Egypt

Bibliografia

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