On the transition from conduction to convection regime in a cubical enclosure with a partially heated wall

Steady-state laminar natural convection in a cubical enclosure with a cold Vertical wall and a hot square sector on the opposite wall is numerically studied. The flow pattern consists of a single, symmetric circulation cell. The transition from conduction to convection regime ends at Ra=10(5), and is characterized by conduction suppression and slow development of convection. In the range of Ra=10(5)-10(7), lateral velocities become very large, producing a highly mixed, thermally stratified three-dimensional flow, and the circulation cell undergoes cross-sectional changes. In the whole range of Ra, the Nusselt number is reduced compared to the case in which the full side wall is hot (test case). (C) 2001 Elsevier Science Ltd. All rights reserved.