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<br />In Figure 4,6 the CSU equation relationship between y~/a and y,/a <br />is given as a function of the Froude number. This relation was <br />developed by Dr, Fred Chang (30). Note that Laursen's pier scour <br />equation is a special case of the CSU equation when the Froude <br />number is 0.4, Values of y /a values around 3.0 were obtained <br />by Jain and Fisher (17) forschute and pool flows with Froude <br />numbers as high as 1,5. The largest value of Ys/a for antidune <br />flow was 2.5 with a Froude number of 1.2. Thus, CSU's equation <br />will correctly predict scour depths for upper regime flows (plain <br />bed, antidunes and chutes and pools). <br /> <br />4 <br /> <br /> r .O~~"," -- 2.3,_ -f- <br /> -I <br /> y c,SU ~~ ~~r <br /> s II 3 ...?: :..--: ~ ~ A. ~~- <br /> -=1.6 (y/oj ~~~~r'O, ~ <br /> o .;':::"" .....-:::: _i;::~-C,SU ~~~r~~ <br /> " ~~- ~~-{.O."2. <br /> - ... ......"'\ Loursen__........Cs\J <br /> ~ <br /> -~ - <br />-- ~ <br /> ~ <br /> ~~- , , <br />~~ y, = Scour Depth <br /> YI = Flow Depth <br /> 0 = Pier Width <br /> <br />2 <br /> <br />~ <br />o <br /> <br />0.8 <br /> <br />0,6 <br /> <br />OA <br /> <br />0.2 <br />0.2 <br /> <br />OA <br /> <br />0,6 0.8 I <br /> <br />2 <br /> <br />4 <br /> <br />6 <br /> <br />8 10 <br /> <br />Y1 10 <br /> <br />Figure 4.6 Values of ys/a vs y,/a for CSU'S Equation (30) <br /> <br />51 <br />