Filamentary vortex in a swirling turbulent flow under strong stretching
  Energy dissipation and pressure fluctuations are features inherent to turbulent fluid motion, and the internal origin of spatial and temporal temperature fluctuations. By measuring local velocity, pressure or temperature, it is possible to detect the presence of coherent structures ---like concentrated vortices--- and quantify their intensity. Here we report measurements of speed and temperature in a filamentary vortex lying in a strongly stretched turbulent airflow. The largest core temperature drop measured in our experiment was $\Delta T = 9$ K, while the fastest measured air speed was $v_{max} = 200$ m/s, which corresponds to a Mach number $M_{max} = 0.59$. At $M \approx 0.1$ temperature drops are on the order of $0.5$ K. These results are consistent with the model for compressible vortices by Aboelkassem and Vatistas [J. Fluids Eng. 129, 1073 (2007)]. 
R. Labb\'e and G. Bustamante
physics.flu-dyn