NUMERICAL INVESTIGATION OF THE STABILIZATION OF THE NO-MOTION STATE OF A FLUID LAYER HEATED FROM BELOW AND COOLED FROM ABOVE

The feasibility of controlling flow patterns of Rayleigh-Benard convec tion in a fluid layer confined in a circular cylinder heated from belo w and cooled from above (the Rayleigh-Benard problem) is investigated numerically. It is demonstrated that, through the use of feedback cont rol, it is possible to stabilize the no-motion (conductive) state, the reby postponing the transition from a no-motion state to cellular conv ection. The control system utilizes multiple sensors and actuators. Th e actuators consist of individually controlled heaters positioned on t he bottom surface of the cylinder. The sensors are installed at the fl uid's midheight. The sensors monitor the deviation of the fluid's temp eratures from preset desired values and direct the actuators to act in such a way so as to eliminate these deviations. The numerical predict ions are critically compared with experimental observations. (C) 1998 American Institute of Physics.