Observation of temperature peaks due to strong viscous heating in a dusty plasma flow

TL;DR

This study observes significant temperature peaks in a dusty plasma flow caused by viscous heating due to shear, supported by measurements of physical properties and dimensionless numbers indicating strong viscous effects.

Contribution

It provides experimental evidence of viscous heating effects in dusty plasma flows and quantifies the phenomenon using measured physical parameters and dimensionless numbers.

Findings

Temperature peaks are observed in high shear regions.

Viscous heating explains the temperature increase.

Dimensionless numbers indicate significant viscous effects.

Abstract

Profound temperature peaks are observed in regions of high velocity shear in a 2D dusty plasma experiment with laser-driven flow. These are attributed to viscous heating, which occurs due to collisional scattering in a shear flow. Using measurements of viscosity, thermal conductivity, and spatial profiles of flow velocity and temperature, we determine three dimensionless numbers: Brinkman Br = 0.5, Prandtl Pr = 0.09, and Eckert Ec = 5.7. The large value of Br indicates significant viscous heating that is consistent with the observed temperature peaks.