NUMERICAL SIMULATION OF FREE OVERFALL IN A ROUGH CHANNEL

This paper reports the results from a turbulent numerical modelling study on the free overfall in a rectangular channel. A wide range of model parameters (i.e. discrete square bar bed roughness, channel slope, and incoming upstream Froude number) is investigated. The water surface profiles, velocity fields and end-depth are simulated and compared with experimental results for various input conditions. The influence of the bed slope, separation of the bar roughness and upstream flow Froude number on the flow structure and free overfall is discussed. The computational results agree well with the experimental measurements.

[1]  Nallamuthu Rajaratnam,et al.  The Rectangular Free Overfall , 1968 .

[2]  Nallamuthu Rajaratnam,et al.  Roughness Effects on Rectangular Free Overfall , 1976 .

[3]  Joel H. Ferziger,et al.  Computational methods for fluid dynamics , 1996 .

[4]  D. Christopherson,et al.  Relaxation Methods Applied to Engineering Problems , 1947, Nature.

[5]  Dirk A. Kraijenhoff,et al.  Brink Depth Method in Rectangular Channel , 1977 .

[6]  M. B. Rubin,et al.  On inviscid flow in a waterfall , 1981 .

[7]  Alastair C. Davis,et al.  Flow Measurement in Sloping Channels with Rectangular Free Overfall , 1998 .

[8]  N. S. Clarke,et al.  On two-dimensional inviscid flow in a waterfall , 1965, Journal of Fluid Mechanics.

[9]  P. Bradshaw,et al.  Turbulence Models and Their Application in Hydraulics. By W. RODI. International Association for Hydraulic Research, Delft, 1980. Paperback US $15. , 1983, Journal of Fluid Mechanics.

[10]  Peter M. Steffler,et al.  Modeling overfalls using vertically averaged and moment equations , 1996 .

[11]  Peter N. Joubert,et al.  Rough wall turbulent boundary layers , 1969, Journal of Fluid Mechanics.

[12]  Subhasish Dey,et al.  Free overall in open channels: state-of-the-art review , 2002 .

[13]  Gillian Vaisey,et al.  Relaxation methods applied to engineering problems XII. Fluid motions characterized by 'free' stream-lines , 1946, Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences.

[14]  L. J. Campbell,et al.  Double-averaged open-channel flow over regular rough beds , 2005 .

[15]  Willi H. Hager,et al.  Hydraulics of Plane Free Overfall , 1983 .

[16]  Kittur G. Ranga Raju,et al.  Resistance to Flow over Two-Dimensional Strip Roughness , 1970 .

[17]  Alastair C. Davis,et al.  Estimating Trajectory of Free Overfall Nappe , 1999 .

[18]  Donald W. Knight,et al.  Hydraulic Resistance of Artificial Strip Roughness , 1979 .

[19]  Yakun Guo,et al.  Numerical Modeling of Free Overfall , 2005 .

[20]  Enrico Marchi,et al.  On the free overfall , 1993 .

[21]  Hunter Rouse,et al.  Discharge Characteristics of the Free Overfall: Use of Crest Section as a Control Provides Easy Means of Measuring Discharge , 1936 .

[22]  G Christodoulou,et al.  BRINK DEPTH METHOD IN RECTANGULAR CHANNEL , 1978 .