The stability of two-dimensional natural convection of water near its density maximum (cold water) inside a vertical rectangular enclosure with an aspect ratio of eight is investigated via a series of direct numerical simulations. The simulations aim to clarify, under the influence of density inversion of cold water, the laminar flow transition from a steady state to an oscillatory state and the instability mechanism for the bifurcation detected for the buoyancy-driven convective flow in the enclosure. Two values of the density inversion parameter, θm = 0.4 and 0.5, where the density inversion of cold water may exert strong influence on the flow, are considered in the present study. The results show that the transition from steady state to periodically oscillatory convection arises in the cold-water-filled enclosure through a Hopf bifurcation. The transitional instability mechanism for both values of 9m is found to have a strong bearing with the instability of the conduction regime of two-dimensional natural convection in a tall vertical enclosure; transition from unicellular into unsteady multicellular structure occurs within the global contra-rotating bicellular flow regions of cold water in the enclosure.
|Number of pages||6|
|Journal||American Society of Mechanical Engineers, Heat Transfer Division, (Publication) HTD|
|Publication status||Published - 1997 Dec 1|
All Science Journal Classification (ASJC) codes
- Mechanical Engineering
- Fluid Flow and Transfer Processes