Journal of Fluid Mechanics


The laminar free surface boundary layer of a solitary wave

Christian A. Klettnera1 p1 c1 and Ian Eamesa1

a1 University College London, Torrington Place, London WC1E 7JE, UK


The laminar free surface boundary layer beneath a solitary wave is investigated using numerical simulations. Across the boundary layer $\partial {u}_{s} / \partial {x}_{n} $ and $\partial {u}_{n} / \partial {x}_{s} $ are comparable in magnitude, where $u$ is the velocity, $x$ position and subscripts $s$ and $n$ refer to components tangential and normal to the free surface. In this region $\partial {u}_{n} / \partial {x}_{s} $ is approximately constant across the boundary layer while $\partial {u}_{s} / \partial {x}_{n} $ varies with ${x}_{n} $ and outside the boundary layer tends to ${\ensuremath{-} } \mathop{ (\partial {u}_{s} / \partial {x}_{n} )} \nolimits _{n= 0} $. The numerical results are compared to analytical models and good agreement is found.

(Received October 29 2011)

(Reviewed December 07 2011)

(Accepted January 26 2012)

(Online publication March 06 2012)

Key Words:

  • boundary layer structure;
  • solitary waves