Granular temperature may control high-speed granular flows, yet it is difficult to measure in laboratory experiments. Here we utilize acoustic energy to measure granular temperature in dense shear flows. We show that acoustic energy captures the anticipated behavior of granular temperature as a function of grain size in quartz sand shear flows. We also find that granular temperature (through its proxy acoustic energy) is nearly linearly proportional to inertial number, and dilation is proportional to acoustic energy raised to the power $0.6\pm 0.2$. This demonstrates the existence of a relationship between granular temperature and dilation. It is also consistent with previous results on dilation due to externally imposed vibration, thus showing that internally and externally induced vibrations have identical results on granular shear flows.

• Received 20 January 2017
• Revised 28 August 2017

DOI:https://doi.org/10.1103/PhysRevE.96.032913