Lagrangian temperature, velocity and local heat flux measurement in Rayleigh-Benard convection

TL;DR

This paper introduces a wireless, neutrally buoyant temperature sensor for Lagrangian measurements in turbulent Rayleigh-Bénard convection, providing insights into flow dynamics and heat transport at high Rayleigh numbers.

Contribution

It presents a novel wireless sensor and optical tracking method for simultaneous position and temperature measurements in turbulent convection.

Findings

Sensor motion resembles Lagrangian tracers in turbulence

Heat transport in plumes shows self-similarity

Significant variations in heat flux between plumes

Abstract

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 $Ra \sim 10^{10}$. 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.