Measurement of turbulent energy balance in Rayleigh Benard convection by liquid crystal thermometry and velocimetry

Heat transport in turbulent rayleigh-Benard convection

We present measurements of the Nusselt number N as a function of the Rayleigh number R in cylindrical cells with aspect ratios 0. 5</=gamma identical withD/d</=12.8 ( D is the diameter and d is the height). We used acetone with a Prandtl number sigma = 4.0 for 10(5) less, similarR less, similar4x10(10). A fit of a power law N = N(0)R(gamma(eff)) over limited ranges of R yielded values of gamma(...

Unsteady Heating of Rayleigh-Benard Convection

The linear thermal instability of a horizontal fluid layer with time-periodic temperature distribution is studied with the help of the Floquet theory. The time-dependent part of the temperature has been expressed in Fourier series. Disturbances are assumed to be infinitesimal. Only even solutions are considered. Numerical results for the critical Rayleigh number are obtained at various Prandtl ...

Surface deflection in Rayleigh-Benard convection

Particle Image Velocimetry and Thermometry using Liquid Crystal Tracers

There are only few techniques allowing an undisturbed and simultaneous monitoring of two important flow characteristics, i.e. temperature and velocity fields. One of such possibilities appeared when thermochromic liquid crystals became commercially available. Initiated almost 15 years ago technique of simultaneous measurement of temperature and velocity fields (Hiller & Kowalewski 1987) recentl...

Critical effects in Rayleigh-Benard convection

2014 The properties of the convection Rayleigh-Bénard phenomenon near its critical threshold of instability are shown to be closely related to those of a second order phase transition. A theory is developed in the framework of the Landau-Hopf hypothesis, and all its predictions are verified by experimental results. Tome 39 N° 7 JUILLET Classification Physics Abstracts 47 . 25Q