Abstract
This research was based on laboratory experiments for hydraulic characteristics for a rectangular
weir with three rectangular bottom openings (equal size of openings, different size of mid opening than an
equal size sides opening. fifty-six physical models were made for this structure with different geometrical
dimensions. Data set are analyzed in order to find the discharge coefficient for three flow cases when water
level (under openings height or between openings height and under crest level and finally through openings
and over the weir) and this analysis is done by using an equation prepared for each flow. Dimensional
analysis was made to relate the discharge coefficient with different geometrical and flow variables for each
flow cases . The highest value of the discharge coefficient, was obtained for flow case no.3, (Cdc = 0.462),
while the lowest value of discharge coefficient was occurred for flow case no.1,(Cdp =0.0193). The
correlation of (Cdp , Cdf , Cdc)was higher negative with (bo/H) with values of (-0.706,-0.937,-0.863)
respectively.
For all the cases tested the coefficient of variation for the discharge coefficient were of range values
(0.5632 - 0.211) which indicate the necessity of obtaining a model to describe this variation.
An ANN models was developed herein using (SPSS software) to express the discharge coefficient
as a function of the different geometrical and flow variables, with range of correlation coefficient for all
models (r=0.999 - 0.941) and applied the results in VISUAL Studio Net,2010 in order to be used by
Engineers to find the discharge coefficient and the actual discharge of each model.
Key words: Hydraulic, Rectangular weir, three Rectangular , bottom openings using ANN