Laserfiche WebLink
<br />\ <br />-( <br />\ <br />cccc~ <br />~~ <br /> <br />CHAPTER 3. CLASSIFICATION OF OPEN CHANNEL FLOW <br /> <br />, <br />" <br />" <br />, <br />, <br /> <br />Section 3.01. r~des of Conveyance <br /> <br />'. <br /> <br />" <br /> <br />The extent to which boundary geometry confines flowing water <br />is a basis for classifying hydraulic problems. If the water surface <br />is free to the atmosphere, open channel flow exists. The other common <br />mode of conveyance is pipe or pressure flow which exists when the sur- <br />face of flowing water is confined, as by a culvert roof. Open channel <br />flow can occur in a culvert provided the depth of water is less than <br />the height of the culvert so that a free surface exists. <br />The importance of this classification is not its effect upon the <br /> <br />, <br />, <br />, <br /> <br />conservation of energy principle. The same one-dimensional energy <br />equation is valid for both open channel and pressure flow. However. <br />the dynamic forces in pressure flow (assuming steady flow) are the <br />viscous and inertial forces. When a free surface exists, the forces <br />of gravity and surface tension must be added to these forces. Also, <br />the position of the water surface is free to change with both time <br />and space: and. consequently. the depth of flow. the discharge, and <br />the slopes of the channel bottom and free surface are interrelated. <br />Open channel flow problems are therefore considerably more difficult <br />to analyze than pressure flow problems. <br /> <br />3.01 <br />