Abstract—Heat transfer and fluid flow due to buoyancy forces in an isosceles prismatic enclosure using the control-volume finite-element method is carried out for different apex angles. This configuration represents solar energy collectors, conventional attic spaces of greenhouses and buildings with pitched roofs. The bottom is submitted to a uniform heat flux, the two top inclined walls are symmetrically cooled and the two vertical walls are assumed to be perfect thermal insulators. Governing parameters, which are effective on flow field and temperature distribution, are; Rayleigh number, aspect ratio of the enclosure and the apex angle. Streamlines, isotherms, velocity and temperature profiles, local and mean Nusselt numbers are presented. It has been found that a pitchfork bifurcation occurs at a critical Rayleigh number, above which the symmetric solutions becomes unstable and asymmetric solutions are instead obtained. It’s also found that the heat transfer decreases with increasing of the apex angle at small Rayleigh number due to quasiconduction dominant heat transfer regime. At the highest Rayleigh number, the increasing of the apex angle enhances the heat transfer.

Index Terms—Natural convection, Apex angle, Aspect ratio, Rayleigh number, Nusselt number, Heat transfer

Cite: Walid Aich and Ahmed Omri, "Natural Convection Flow Simulation for Various Apex Angles in Heated Prismatic Cavity," International Journal of Mechanical Engineering and Robotics Research, Vol. 3, No. 1, pp. 241-255, January 2014.