Experimental study of surface wave phenomena on a vertically sheared current*

We present an experimental study of surface waves on a sheared current. The experiments were performed in a newly built laboratory at the Norwegian University of Science and Technology. A shear current with a free surface is created in two different ways: with a curved mesh upstream, and in a region where an obstacle near the surface creates an area upstream of it where the surface is stagnant, and the sub-surface flow is strongly sheared. We present qualitative and quantitative observations of surface waves, wave dispersion and shear effects in the real and Fourier planes, and compare with theoretical results from a recently developed theoretical framework for initial waves on a current with arbitrary vertical shear.