Related Experiment Video
Updated: Feb 15, 2026

Ultrasound Velocity Measurement in a Liquid Metal Electrode
Published on: August 5, 2015
Low Rm magnetohydrodynamics as a means of measuring the surface shear viscosity of a liquid metal: A first attempt on
Jules Delacroix1, Laurent Davoust1, Kévin Patouillet1
1Electromagnetic Processing of Materials (EPM), SIMaP, Université Grenoble-Alpes, CNRS, Grenoble-INP (Institute of Engineering Université Grenoble Alpes), 38402 Saint-Martin d'Hères, France.
Abstract:
This paper introduces an experimental apparatus which generates the end-driven annular flow of a liquid metal pervaded by a uniform magnetic field. Unlike past viscometers involving an annular channel with particular values of the depth-to-width ratio, the present experiment enables us to drive the viscous shear at the surface of an annular liquid metal bath put in rotation. The magnetic interaction parameter N and the Boussinesq number related to the surface shear viscosity can be monitored from the magnitude of the applied magnetic field; the latter being set large enough for avoiding artefacts related to centrifugation and surface dilatation. This essential feature is obtained due to the ability of the magnetic field to set dimensionality of the annular flow in the channel between 2D-1/2 (swirling flow) and 2D axisymmetric (extinction of the overturning flow if N is large enough). By tracking the azimuthal velocity of tracers seeded along the oxidised surface of liquid Galinstan, an estimate for the surface shear viscosity of a liquid metal can be given.
Related Concept Videos
Surface Tension, Capillary Action, and Viscosity
The various IMFs between identical molecules of a substance are examples of cohesive forces. The molecules within a liquid are surrounded by other molecules and are attracted equally in all directions by the cohesive forces within the liquid. However, the molecules on the surface of a liquid are attracted only by about one-half as many molecules. Because of the unbalanced molecular attractions on the surface molecules, liquids contract to form a shape that minimizes the number...
Viscosity
The SI unit of viscosity is...
Viscosity of Fluid
Bonding in Metals
Metallic Solids
All metallic solids exhibit high thermal and electrical conductivity, metallic luster, and malleability....
Alkali Metals
Table 1: Properties of the alkali metals

