Computation of leading-edge contamination

Subcritical instability on the attachment-line of an infinite swept wing

“…For infinite strength of the vortex, impulsive start caused the unsteady boundary layer to thicken and recirculating eddies to develop owing to self-imposed adverse pressure gradient. Thus, the present study and those given in SDS and Sengupta et al (2004) are qualitatively different where the coherent eddies are formed inside a steady boundary layer. In SDS and Lim et al (2004), the receptivity mechanism was shown to be a strong function of strength, core size, sign and distance of the convecting vortex from the shear layer.…”

“…Secondly, the vortices were directed toward the wall, unlike the present case where the vortex moves parallel to the wall at a constant speed. Finally, the vortices in Obrist & Schmid (2003b) were constrained to move with the free-stream speed, while in Sengupta et al (2004) and here, the vortex moves at different speeds and the results identify translational speeds for which receptivity is significant.…”

“…Hence, this problem continues to hold interest as seen by recent publications, see e.g. Theofilis et al (2003), Obrist & Schmid (2003a, b) and Sengupta et al (2004). A good introduction to leading-edge contamination (LEC) is provided in Theofilis et al (2003) which summarizes that 'there exist two most significant unresolved issues in the stability of the attachment-line boundary layer.'…”

“…In SDS and Lim et al (2004), the receptivity mechanism was shown to be a strong function of strength, core size, sign and distance of the convecting vortex from the shear layer. In Sengupta et al (2004), this model has been tested and computational results reported that show that sub-critical instability is triggered in the attachment-line boundary layer. In this paper, we discuss the mechanism of LEC with the help of the receptivity equation developed in SDS and provide various estimates of the ensuing spatio-temporal instability.…”

“…The computational domain chosen here is such that it can only suffer sub-critical instability. Sengupta et al (2004) investigated eight cases for different parameters, indicating their relative importance. Here, a longer computational domain is used to trace the vortex-induced instability over longer distances and the physical mechanism behind LEC is explained.…”