Shock-Induced Dynamics of a Low-Density Heated-Fluid Element
Abstract
The dynamic behavior of a two-dimensional, heated, turbulent fluid element which is instantaneously set into motion relative to its surroundings by the passage of a reflected shock wave has been studied in a shock tube. It is demonstrated that the dynamics of this fluid element are similar to those encountered in the study of gravitational thermals, and that the shock tube may be used to extend the range of experimental parameters under which "thermal-like" phenomena can be investigated. An exploding wire was used to generate the clearly defined heated element. Data obtained from high-speed (22 000 pictures/sec) interferograms indicate that the effective radius (re) of the heated element varies linearly with its horizontal displacement (x), i.e., re = αx, where α, the entrainment coefficient, is a constant. The coefficient α is shown to vary approximately linearly in the range 0.15 ≲ α ≲ 0.50 with increasing shock strength. The observed temporal growth of the heated element was compared with that predicted analytically from a semiempirical application of the mass and momentum conservation relations.
- Publication:
-
Physics of Fluids
- Pub Date:
- July 1972
- DOI:
- 10.1063/1.1694073
- Bibcode:
- 1972PhFl...15.1248H