9 research outputs found
Lagrangian temperature, velocity and local heat flux measurement in Rayleigh-Benard convection
We have developed a small, neutrally buoyant, wireless temperature sensor.
Using a camera for optical tracking, we obtain simultaneous measurements of
position and temperature of the sensor as it is carried along by the flow in
Rayleigh-B\'enard convection, at . We report on statistics of
temperature, velocity, and heat transport in turbulent thermal convection. The
motion of the sensor particle exhibits dynamics close to that of Lagrangian
tracers in hydrodynamic turbulence. We also quantify heat transport in plumes,
revealing self-similarity and extreme variations from plume to plume.Comment: 4 page
Shear Effects in Non-Homogeneous Turbulence
Motivated by recent experimental and numerical results, a simple unifying
picture of intermittency in turbulent shear flows is suggested. Integral
Structure Functions (ISF), taking into account explicitly the shear intensity,
are introduced on phenomenological grounds. ISF can exhibit a universal scaling
behavior, independent of the shear intensity. This picture is in satisfactory
agreement with both experimental and numerical data. Possible extension to
convective turbulence and implication on closure conditions for Large-Eddy
Simulation of non-homogeneous flows are briefly discussed.Comment: 4 pages, 5 figure
Evidences of Bolgiano scaling in 3D Rayleigh-Benard convection
We present new results from high-resolution high-statistics direct numerical
simulations of a tri-dimensional convective cell. We test the fundamental
physical picture of the presence of both a Bolgiano-like and a Kolmogorov-like
regime. We find that the dimensional predictions for these two distinct regimes
(characterized respectively by an active and passive role of the temperature
field) are consistent with our measurements.Comment: 4 pages, 3 figure