Spatial correlation of temperature in turbulent Rayleigh-Benard convection

Abstract

A cubic Rayleigh-Benard cell is operated at a Rayleigh number of 1.5x10(9) and a Prandtl number of 6.1. The cell is equipped with thermistors placed along the vertical line through the center of the cell. The spatial correlation of temperature is deduced from simultaneous temperature recordings from these thermistors. The correlation function is well fitted by the sum of two exponentials. There is no cascade in the temperature field as only two characteristic length scales appear. The direct measurement of spatial correlations allows us to test the validity of Taylor's hypothesis in this flow.