Analysis of Near-Field Hydrodynamics of Submerged Weirs
ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS COASTAL AND HYDRAULICS LAB
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This Coastal and Hydraulics Engineering Technical Note presents the results of three-dimensional numerical model simulations of Victoria Bendway in the Mississippi River. The primary purpose of this study was threefold a to better understand the near field hydrodynamics adjacent to submerged bendway weirs, b to provide insight into the effectiveness of submerged weirs for improving navigation in bendways, and c to determine optimum design variables and flow conditions for improving weir field design. Over the last decade, the U.S. Army Corps of Engineers has been constructing submerged weirs in river bends to improve navigation conditions and consequently reduce dredging. The most effective prototype submerged weir fields were initially evaluated in small-scale physical models Waterway Simulation Technology, Inc., 1999.1 However, some weir fields are currently designed and constructed based on the success of previous installations and very little design guidance. A summary of bendway weir construction practices was prepared as an initial design guide for submerged weir installations LaGrone 1995.2 It provides a qualitative approach to bendway weir design based on information gleaned from experts involved in previous weir field installations. The primary function of submerged weirs is to realign the flow by reducing or disrupting the bendway secondary helical flows. In bendways without weirs, the transverse helical flow resulting from centrifugal forces redirects the surface flow against the outer bank. Tow navigation entering the bendway tends to follow the flow lines and is therefore forced toward the outside bank. The tow must then execute maneuvers to realign within the channel thalweg, risking collision with the outer bank or running aground on the shallow point bar adjacent to the inside of the bend.
- Hydrology, Limnology and Potamology
- Numerical Mathematics
- Fluid Mechanics