DYNAMICS AND SCALING IN QUASI-2-DIMENSIONAL TURBULENT CONVECTION

High Rayleigh number (4 x 10(4)-3 x 10(7)) quasi-two-dimensional conve ction is studied experimentally, numerically, and theoretically. The f luid is contained in an isothermal Ht le-Shaw cell, which enforces the two dimensionality, and the convection is driven by an externally imp osed vertical concentration gradient. The full two dimensional concent ration held is imaged experimentally and is sampled at regular interva ls spanning between five and fifty convective times (the time it takes a plume to cross the cell). The most prominent and dynamically signif icant features of the flow are solutal plumes which form within the co ncentration boundary layer, Tip splitting of plumes leading to smaller length scales and merging of plumes leading to larger length scales a re observed, A model of Hele-Shaw convection, which includes a frictio n term due to the boundaries parallel to the velocity field, is simula ted, The evolution of the pattern and dynamics of the concentration fi eld as well as time averaged spatial spectra, are obtained from the ex periment and simulation, Results fur exponents which describe how the Nusselt number and Reynolds number scale with Rayleigh number are obta ined theoretically and compared with the values from simulation.