Please use this identifier to cite or link to this item: https://hdl.handle.net/11681/3483
Title: Mechanics of bottom sediment movement due to wave action
Authors: University of California, Berkeley. Wave Research Laboratory
United States. Army. Office of the Chief of Engineers
Manohar, Madhav, 1924-
Keywords: Beach erosion
Sediments
Sedimentation and deposition
Water waves
Sediment transport
Onshore-offshore movement
Publisher: United States, Beach Erosion Board
Engineer Research and Development Center (U.S.)
Series/Report no.: Technical memorandum (United States. Beach Erosion Board) ; no. 75.
Description: Technical Memorandum
Abstract: Up to the present time, very few experimental or analytical studies have been made on the effect of the action of surface waves on the moverrent of sediment at the bottom. Some of these studies have been limited to a few experinental observations, while others are expressed only in general descriptive terms. In the present study, as a result of an analytical and experimental investigation, it is found that, because of the action of surface waves, there are initial and general movements of sediment; and initiation, various stages of development, and complete disappearance, of bed undulations or ripples. The movement of sediment takes place in a boundary layer that is developed at the bottom from the effects of viscosity of the fluid. The initial and general motion of small sizes of sediment occur in a laminar boundary layer and are caused by laminar shear, while similar motions of large sizes of sediment are caused by lift forces in a turbulent boundary layer. Ripples, in general, are not formed unless the now is turbulent in the boundary layer. All motion in turbulent now and the various stages of development of ripples are found to be functions of a dimensionless function representing intensity of flow of the fluid near the bottom. Flow conditions in the boundary layer at the interface are distinguished by the ratio of the thickness of the boundary layer to the size of the sediment. These phenomena of initiation of turbulence and motion of sediment in the boundary layer at the bottom are expressed in terms of the characteristics of the surface waves.
URI: http://hdl.handle.net/11681/3483
Appears in Collections:Technical Memorandum

Files in This Item:
File Description SizeFormat 
BEB-TM-75.pdf6.18 MBAdobe PDFThumbnail
View/Open