Three‐dimensional streaming in the seabed boundary layer beneath propagating waves with an angle of attack on the current. Issue 6 (17th June 2015)

• Record Type: Journal Article
• Authors: Afzal, Mohammad Saud; Holmedal, Lars Erik; Myrhaug, Dag
• Is Part Of: Journal of geophysical research. Volume 120:Issue 6(2015:Jun.)
• Page Start: 4370
• Page End: 4391
• Publication Date: 2015-06-17
• Subjects: Oceanography -- Periodicals; 551.4605
• DOI: 10.1002/2015JC010793
• Languages: English
• ISSNs: 2169-9275

Abstract

<abstract abstract-type="main"> <title>Abstract</title> <p>The effect of three‐dimensional wave‐induced streaming on the seabed boundary layer is investigated for following and opposing waves and current where the wave propagation forms a nonzero angle with the current. It is shown that the seabed boundary layer flow results from an interaction between the classical wave‐current interaction (reducing the mean velocity relative to current alone), Longuet‐Higgins streaming (forcing the flow in the wave propagation direction), and streaming caused by turbulence asymmetry in successive wave half‐cycles (forcing the flow against the wave propagation direction). For waves and current which are not colinear, the mean velocity profile exhibits a veering behavior which is strongly affected by streaming, particularly for the most wave‐dominated situations. The effect of streaming on the boundary layer flow has been investigated for different wave‐current conditions and bottom roughnesses. Visualizations are given by mean Eulerian and Lagrangian velocity profiles, as well as three‐dimensional seabed boundary layer particle trajectories. The effect of streaming decreases as the flow becomes more current dominated. The mean velocity in the current direction decreases as the roughness increases. However, the mean velocity orthogonal to the current direction increases as the roughness increases due to the lack of wave‐current interaction in this direction. An excellent agreement between the predicted and recently measured velocity profiles beneath horizontally uniform asymmetric forcing is obtained.</p> </abstract>