CFD analysis of turbulent heat transfer characteristics in cubical enclosure

Abstract

In this paper we present the turbulent flow and convective heat transfer phenomena inside a cubical enclosure with an internal heat source. The enclosure is designed with an inlet and outlet vent and the heat source is mounted on the bottom wall. The turbulent flow is modeled by the computational fluid dynamics (CFD) approach using Lambremhorst k-ε turbulence model. A finite difference method is used to discretize the governing equations and an in-house CFD used is developed for simulating the turbulent characteristics. The parametric study is performed for the assisting and opposing flow character stics inside the enclosure by varying the Grashof (Gr) and Reynolds (Re) number in the range of 105 ≤ Gr ≤ 1010 and 102 ≤ Re ≤ 106. The present study emphasises that the inertial force and buoyancy force has significant impact on the recirculation flow p attern inside the enclosure. The heat transfer rate is drastically influenced by the assisting and opppsing flow behavior developed inside the enclosure. It is observed that the mass flow rate across the outlet vent increases linearly with the Reynolds nu mber. The flow behavior is highly chaotic with the development of instabilities inside the enclosure. The streamlines and temperature distribution patterns inside the enclosure indicated that the assisting flow enhanced the heat transfer rate by 48% while the opposing flow suppressed the heat transfer rate by 45% inside the enclosure. A multi recirculating convective cell pattern is formed at higher Grashof number and the size of the cell increases with increase in Grashof number. It is also found that the mass flow rate across the outlet vent increases linearly for assisting flow case while it decreases for the opposing flow case. It is evident from the present study that the assisting flow case is best suited for heat transfer enchancement in cubical enclosure.