Development of a wall plume from a boundary layer along a partially heated vertical wall

Transient natural convection flow along a partially heated vertical wall was studied experimentally, using schlieren flow Visualization, temperature measurements and particle image velocimetry. Departing from a motionless and in thermal equilibrium state, motion was generated by increasing the temperature of the lower half wall while the top half was thermally insulated. Four main events were registered: 1) Firstly, in the lower half wall, the boundary layer thickened and the flow started to ascend. 2) A group of waves traveled along the boundary layer. 3) From heated wall/adiabatic wall point, a starting plume was formed and a vortex was generated which moved towards the free surface. 4) Behind the vortex. a wall plume was formed leading to a steady state. Temperature difference between the heated wall and the fluid was varied in order to achieve conditions with three different Rayleigh numbers of 2.0 x 10(9), 4.9 x 10(9) and 8.9 x 10(9). The nondimensional velocity of the ascending vortex was described in terms of the product Ra(1/2)Pr(-1/2). (C) 2004 Elsevier Science Ltd.