Abstract
The use of streamwise grooves for intensification of streaks created by heating in shear layers has been investigated. Three ranges of groove wave numbers were of interest: wave numbers near the critical wave number of the Rayleigh-Bénard (RB) instability, wave numbers characterizing drag-reducing grooves, and the optimal wave numbers. It is shown that uniform heating of a grooved surface produces intense streaks only when the groove wave number is near the critical RB wave number and the heating intensity exceeds the critical RB intensity. The use of long-wavelength grooves reduces flow losses, but the resulting streaks are less intense. The use of heating patterns tuned with groove patterns can produce very intense streaks whose spatial distribution is easily controlled through selection of the patterns’ wave number. An increase of flow losses due to patterned heating can be compensated for using spatial groove distributions with drag-reducing capabilities. It has been demonstrated that the most effective wave number producing high-intensity streaks at low flow losses is between the RB wave number and the drag-reducing wave numbers—this optimal wave number has been identified.
3 More- Received 17 April 2022
- Accepted 22 July 2022
DOI:https://doi.org/10.1103/PhysRevFluids.7.083502
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