An experimental investigation of the combined effects of surface curvature and streamwise pressure gradients both in laminar and turbulent flows

The amplification of large-scale motion in a supersonic concave turbulent boundary layer and its impact on the mean and statistical properties

“…In addition to the enhancement of turbulent levels in a concave turbulent boundary layer, the wall friction and heat transfer coefficients are also increased relative to their canonical flat-plate values (see e.g. Smits & Wood 1985;Ozalp & Umur 2003).…”

A DNS study on the effects of streamwise convex surface curvature on coherent structures in turbulent boundary layers

“…The mean tem perature profiles in the boundary layer on a convex surface are less full than the corresponding profiles on the flat surface sim ilar to the behaviour o f the mean velocity profiles. The value o f the Stanton num ber (St=h/pumCp, where h is the convection heat transfer coefficient, p is the flow density, ux is the freestream velocity, Cp is the specific heat at constant pressure) is slightly m ore affected by convex surface curvature as it is reduced to 82% compared to Cf reducing to 88% o f that on the flat surface (Gibson and V erriopoulos, 1984;Ozalp and Umur, 2003). where s, t and u denote the local (elem ent-based) coordinates.…”

“…The m ixing-length theory developed by Prandtl (1925) is the first such theory that relates the Reynolds stresses to the mean flow field by an effective eddy viscosity or m ixing length to curvature) for the convex surface but Liepmann (1943) found that convex-surface curvature in the range used in his experim ents did not have an appreciable effect on transition as com pared to the flat surface. The stabilizing influence o f convex-surface curvature can also be expected to delay the transition to turbulence w hich would result in a higher shape factor and a lower interm ittency factor com pared to a flat surface (Ozalp and Umur, 2003;U m ur and Ozalp, 2006).…”

“…However, there is some disagreem ent with regards to the growth rate o f the m om entum thickness Reynolds num ber in the flat surface and convex surface boundary layers. M eroney andBradshaw (1975) observe a reduced momentum thickness growth rate while O zalp andUmur (2003) observe a higher growth rate on the convex surface;Ramaprian and Shivaprasad (1977) find that the growth rate o f the m om entum -thickness Reynolds num ber decreases initially but increases later on the convex surface in com parison to the flat surface Ramaprian and Shivaprasad (1977). attribute the initial decrease in the m om entum thickness growth rate to a possible result o f the sudden introduction o f flow to curvature from initial flat surface conditions and the later increase in the mom entum thickness growth rate to the flow being subjected to sustained curvature.…”