a1 Department of Civil, Environmental and Architectural Engineering, Genoa University, via Montallegro 1, 16145 Genova, Italy
A linear stability analysis of the laminar flow in the boundary layer at the bottom of a solitary wave is made to determine the conditions leading to transition and the appearance of turbulence. The Reynolds number of the phenomenon is assumed to be large and a ‘momentary’ criterion of instability is used. The results show that the laminar regime becomes unstable during the decelerating phase, when the height of the solitary wave exceeds a threshold value which depends on the ratio between the boundary layer thickness and the local water depth. A comparison of the theoretical results with the experimental measurements of Sumer et al. (J. Fluid Mech., vol. 646, 2010, pp. 207–231) supports the analysis.
(Received November 29 2011)
(Reviewed April 18 2012)
(Accepted July 02 2012)
(Online publication August 24 2012)