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Hydrodynamic modelling study of a fish exclusion system for a river diversion
Author(s) -
Ho J.,
Coonrod J.,
Hanna L. J.,
Mefford B. W.
Publication year - 2011
Publication title -
river research and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.679
H-Index - 94
eISSN - 1535-1467
pISSN - 1535-1459
DOI - 10.1002/rra.1349
Subject(s) - mechanics , porous medium , baffle , reynolds number , flow (mathematics) , reynolds averaged navier–stokes equations , flow velocity , obstacle , hydraulic head , computational fluid dynamics , porosity , materials science , geology , turbulence , geotechnical engineering , physics , mechanical engineering , engineering , political science , law
Abstract River diversions are often equipped with some device to exclude fish, such as fish screens. Flow pattern changes due to fish screen systems were investigated using a three‐dimensional numerical model solving the Reynolds‐averaged Navier‐Stokes (RANS) equations. A porous media obstacle, which is commonly used for ground water flow modelling, was employed to model a fish screen. Fish screens require a velocity component perpendicular to the screen (approach velocity), allowing for water diversion. Meanwhile, it is imperative that this velocity not result in pinning fish to the screen but allowing for fish to be guided to a different location. Thus the ratio of sweeping velocity to approach velocity ( V R ) is an important criterion in fish screen design. 20:1 V R and 10:1 V R models were tested under high and low flow rates in this study. Screen head loss coefficients for various wire Reynolds numbers were compared with laboratory model measurements to verify the mathematical results. Two different screen types were simulated: perforated plate and wedged wire. Altering global porosity and local permeability of a porous obstacle results in flow direction changes that effectively simulate different screen materials in the numerical model. Model simulations of head loss coefficients and velocity ratios showed good agreement with the laboratory model measurements. The wedged wire allows for more control of the velocity ratio along the screen system than the perforated plate. Baffles installed behind each fish screen bay promote uniform flow distribution along the screen. The porous media obstacle assumption is shown to effectively simulate the hydraulics of various configurations of fish screens at river diversion channels. Copyright © 2010 John Wiley & Sons, Ltd.