Boundary layer flows over concave surfaces are subject to a centrifugal instability that leads to spatially growing longitudinal vortices known as Gortler vortices. From the practical standpoint, this phenomenon can be encountered, for example, in flows evolving over the concave part of a wing or turbomachinery blade, or on the walls of diverging-converging nozzles such as those utilized in supersonic/hypersonic wind tunnels. Depending on the curvature, the Reynolds number of the flow, and the level of environmental disturbances, these vortices can first lead to secondary instabilities, potential vortex breakdown, and eventual transition to turbulence. Here, we investigate the effect of varying the wall temperature on the development of Gortler vortices in high-speed boundary layer flows (with free-stream Mach number ranging from 1.5 to 7), using direct numerical simulations of the Navier-Stokes equations. The results reveal that the cooling of the wall can reduce the wall skin friction commensurately with the decrease in wall temperature, but at the same time increases the energy of the Gortler vortices.
|Number of pages||1|
|Publication status||Published - 18 Nov 2018|
|Event||71st Annual Meeting of the APS Division of Fluid Dynamics: Boundary Layers: High Speed/ Compressible - Georgia World Congress Center, Georgia, United States|
Duration: 18 Nov 2018 → 21 Nov 2018
|Conference||71st Annual Meeting of the APS Division of Fluid Dynamics|
|Abbreviated title||APS-DFD 2018|
|Period||18/11/18 → 21/11/18|
- boundary layer flow
- Gortler vortices
Sescu, A., El-Amrani, S., & Afsar, M. Z. (2018). Effect of wall temperature on the growth of Gortler vortices in high-speed boundary layers. Abstract from 71st Annual Meeting of the APS Division of Fluid Dynamics, Georgia, United States.