Laminar natural convection in a square enclosure with discrete heating of vertical walls

Abstract EN

Natural convection heat transfer in a square air-filled enclosure with one discrete flush heater is examined numerically.

The enclosure is vertical with isothermal heating strip on one wall, the remainder of the wall and the opposing one are isothermally maintained at a lower temperature.

The top and bottom sides are adiabatic.

The two dimensional differential conservation equations of mass, momentum and energy are solved by a finite difference method for Rayleigh number varying from 102 to 106.

The changes in temperature and flow fields (stream functions) with increase in Rayleigh number are investigated for different heater locations.

The isothermal cold sections adjacent to the heater assist the development of secondary circulation cells, that depend upon both Rayleigh number and the position.

With discrete heating and cooling sections on one wall, the flow is characterized by boundary layers lining these sections with separate circulation cells.

The variation of the local Nusselt number is influenced by this flow pattern and the average Nusselt number is higher than that of a discrete heating strip mounted on an adiabatic wall.

The optimum location over the range of Rayleigh number is for the heater mounted at the center of the wall, s / L = 0.5 a result confirmed by previous experiments.