Local Lorentz force and ultrasound Doppler velocimetry in a vertical convection liquid metal flow

TL;DR

This study combines local Lorentz force and ultrasound Doppler velocimetry to measure and analyze turbulent convection flows in liquid metal, validating measurement techniques and exploring heat and momentum transport scaling laws.

Contribution

It demonstrates the applicability of LLFV in thermal convection flows and investigates scaling laws in low-Prandtl-number turbulence, aligning with theoretical and numerical predictions.

Findings

LLFV force scales linearly with flow velocity

Results agree with theoretical predictions

Insights into turbulent heat and momentum transport

Abstract

We report velocity measurements in a vertical turbulent convection flow cell that is filled with the eutectic liquid metal alloy gallium-indium-tin by the use of local Lorentz force velocimetry (LLFV) and ultrasound Doppler velocimetry (UDV). We demonstrate the applicability of LLFV for a thermal convection flow and reproduce a linear dependence of the measured force in the range of micronewtons on the local flow velocity magnitude. Furthermore, the presented experiment is used to explore scaling laws of the global turbulent transport of heat and momentum in this low-Prandtl-number convection flow. Our results are found to be consistent with theoretical predictions and recent direct numerical simulations.