Published online by Cambridge University Press: 13 July 2012
In this paper we present a set of wave flume experiments for a solitary wave reflecting off a vertical wall. A particle tracking velocimetry (PTV) technique is used to measure free-surface velocity and the velocity field in the vicinity of the moving contact line. We observe that the free surface undergoes the so-called rolling motion as the contact line moves up and down the vertical wall, and fluid particles on the free surface almost always flow toward the wall except at the end of the reflection process. As the contact line descends along the wall, wall boundary layer flows move in a downward direction and therefore the boundary layer acts like a conduit through which the surface-rolling-induced flow escapes from the meniscus. However, during the last phase of the reflection process flow reversal occurs inside the wall boundary layer. An approximate analytical solution is developed to explain the flow reversal feature. Very good agreement between the approximate theory and measured data is obtained. Because of the flow reversal, boundary layer flows collide with the surface-rolling-induced flows. The collision gives rise to a jet ejecting from the meniscus into the water body, which later evolves into a small eddy. It is noticed that the fluid particles in different regions such as the free stream, the free-surface boundary layer and the wall boundary layer, can be transported to other regions by passing through the meniscus.
The movie shows the formation of the jet as well as the induced clockwise eddy during the last phase of the solitary wave reflection. Note that we only include every fifth frame in the movie to reduce the file size, and it is ten times slower than the real time. At the frame in which the jet is formed, the red half-circle in the movie indicates the locations of the jet.
The movie shows the formation of the jet as well as the induced clockwise eddy during the last phase of the solitary wave reflection. Note that we only include every fifth frame in the movie to reduce the file size, and it is ten times slower than the real time. At the frame in which the jet is formed, the red half-circle in the movie indicates the locations of the jet.