VARIATION OF TEMPERATURE AND VELOCITY FLUCTUATIONS IN TURBULENT THERMAL-CONVECTION OVER HORIZONTAL SURFACES

The variations of root-mean-square (r.m.s.) temperature and velocity i n turbulent thermal convection above a heated, horizontal surface are analyzed by extending the arguments of Castaing ei al. ([1]: J. Fluid Mech. 204, 1-30 (1989)) which lead to the two-sevenths power law for h eat transfer. Asymptotic matching of properties scaled on Deardoff's c onvection scales with those scaled on Castaing et al.'s lambda-layer s how that the r.m.s. temperature decays as z(-1/2) and the r.m.s. verti cal velocity increases as log z. These results are supported by data f rom Rayleigh convection and unsteady convection,both penetrative and n on-penetrative. Copyright (C) 1996 Elsevier Science Ltd.