Frontiers in Heat and Mass Transfer (FHMT), 5, 12 (2014) DOI: 10.5098/hmt.5.12 Global Digital Central ISSN: 2151-8629 1 NUMERICAL ANALYSIS OF NATURAL CONVECTION IN A RIGHT- ANGLED TRIANGULAR ENCLOSURE Manoj Kr. Triveni * , Dipak Sen, RajSekhar Panua National Institute of Technology, Agartala, Tripura, 799055, India ABSTRACT A numerical investigation has been performed for heat transfer analysis in a right-angled triangular enclosure filled with water. The side wall of the enclosure is maintained at high temperature compare to the base wall while hypotenuse is kept thermally insulated. Two - dimensional steady-state continuity, momentum and energy equations along with the boussinesq approximation are solved by finite volume method using commercial available software, FLUENT 6.3. The computational results are shown in terms of isotherms, streamlines and velocity contour for Rayleigh number (10 5  Ra  10 7 ). The heat transfer is presented in terms of local and average Nusselt number. The result encapsulates that both flow field and temperature distributions are affected with Rayleigh number. The simulated results are validated with the experimental and numerical results and it shows a good agreement with the published results. Finally, a correlation for Nusselt number (Nu) with Rayleigh number (Ra) has been developed for vertical hot wall. Keywords: Natural convection, Triangular enclosure, Rayleigh number, Numerical simulation. * Corresponding author. Email: triveni_mikky@yahoo.com 1. INTRODUCTION Many researchers have been working on natural convection using a triangular cavity due to its wide applications in building insulation, solar collector and electronic equipments. Akinsete and Coleman (1982) were used a numerical technique to investigate the laminar natural convection in air contained in a long horizontal right-triangular enclosure. Steady-state solutions had been obtained for height-base ratios of 0.0625 </ H/B ⩽ 1.0 for Grashof number of 800 ⩽ Gr (B) ⩽ 64 000. Results were reported that the heat transfer across the base wall increases towards the hypotenuse/base intersection such that the third of the base length nearest the intersection accounts for about 60% of the heat transferred across the base. Asan and Namli (2000) have carried out a numerical study for laminar natural convection in a pitched roof cross section under summer day boundary conditions. Problem was solved for different height – base ratio and Ra = 10 3 – 10 6 . Aydin and Yesiloz (2011) have studied the buoyancy induced flow and heat transfer mechanisms in a water-filled quadrantal cavity experimentally and numerically. It has been concluded from the investigation that the influence of Rayleigh number is insignificant at Ra< 10 3 and it becomes significant beyond 10 4 . Basak et al. (2012) have worked on entropy generation due to natural convection in right-angled triangular enclosures filled with porous media. It was observed that the total entropy generation is increasing function of Darcy number. Ghasemi and Aminossadati (2010) have done a numerical study on natural convection in right triangular enclosure with heat source on its vertical wall and water-CuO nanofluid as a source medium. Parameters such as Rayleigh number, solid volume fraction, heat source location and enclosure aspect ratio which affect the heat transfer rate were examined. Enhancement in heat transfer was observed for upper location of heat source and high aspect ratio for high Rayleigh number. Kaluri et al. (2010) have analyzed natural convection in right-angled triangular enclosures with various top angles. It was observed that for lower angle (15 0 ), the average nusselt number remains invariant with increase in Ra, but the enhanced convection at higher Ra significantly affects the heat flow distribution. Kent (2009) has done a numerical analysis in an isosceles triangular cavity by varying the aspect ratio and base angle from 15 o to 17 o . The lower aspect ratio has high heat transfer rate from the bottom surface of the triangular enclosure. Ridouane et al. (2005) have numerically computed laminar natural convection in a right-angled triangular cavity filled with air. The vertical side wall is considered as hot wall while cooling is done from hypotenuse of the triangular enclosure. It was examined that the heat transfer enhancement get decreased when both apex angle and Rayleigh number diminishes. Saha (2011) has inspected the heat transfer and fluid flow in a triangular enclosure for instantaneous heating on the inclined walls. Investigation shows that the nusselt number was very high initially due to conduction effect and after that it decreases gradually and become steady state. Sun and Pop (2011) were numerically investigated the heat transfer behavior of nanofluids in a triangular enclosure filled with porous medium. Heat transfer rate was solved for different parameters such as Rayleigh number (Ra), size of heater (Ht), position of heater (Yp) and enclosure aspect ratio. The maximum value of average Nusselt number is obtained for decreasing aspect ratio, lowering the heater position with the highest value of Rayleigh number and the largest size of heater. Also, heat transfer is enhancing with the increasing of solid volume fraction at low Rayleigh number. Tzeng et al. (2005) proposed the Numerical Simulation Aided Parametric Analysis method to solve natural convection equations in streamline- vorticity form. Varol et al. (2006) used a flush mounted heater on side wall of the triangular cavity. Aspect ratio of the triangle, location of heater, length of heater and Rayleigh number are some parameters which considered for heat transfer analysis. It was reported that the heat transfer is Frontiers in Heat and Mass Transfer Available at www.ThermalFluidsCentral.org