Local heat/mass transfer distributions on the bottom surface of a cavity exposed to an approaching turbulent boundary layer

Heat/mass transfer on the bottom surface of a rectangular cavity in an incompressible turbulent bound-ary layer flow is investigated, with emphasis on the effects of cavity width (W) to depth (d) ratio, for a cavity with aspect ratio L/d (length L to depth) of 6. For a wide cavity, this value of L/d is known to establish a flow structure in which the streamwise flow does not reattach on the bottom surface of the cavity, and instead shears past the entire open surface of the cavity, impinging on the downstream wall. A naphthalene sublimation mass transfer technique is used to evaluate local (mass) Stanton num -bers at the cavity bottom surface for W/d ranging from 0.51 to 10, and two Reynolds numbers of 8100 and 12,800 defined using the cavity depth and freestream velocity. For W/d 2 , the area-averaged Stanton number decreases as width is reduced, scaling as a power law with W/d, and appears to be independent of Reynolds number. Computations using the SST k - omega RANS model are able to predict the measured heat/mass transfer at the bottom surface well for W/d 3 . For 0 . 8 < W/d < 3 , the computations are able to capture the trends only qualitatively. For W/d < 0 . 8 , computations fail to predict the observed distri-butions and significantly under-perform. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This study investigates the heat/mass transfer on the bottom surface of a rectangular cavity in an incompressible turbulent boundary layer flow. The effects of cavity width to depth ratio are examined, and the results show that the transfer decreases as the width is reduced, regardless of the Reynolds number. The computational model is able to predict the transfer accurately for larger cavity widths, but performs poorly for smaller widths.