Laserfiche WebLink
<br />Chapter 4 Example Application <br /> <br />Reach lengths across the junction are entered in the junction editor, rather than <br />in the cross section data. This allows for the lengths across very complicated <br />confluences (i.e. flow splits) to be accommodated. In the cross section data, <br />the reach lengths for the last cross section of each reach should be left blank <br />or set to zero. <br /> <br />In this example the energy equation will be used to compute the water surface <br />profile through the junction. If the momentum equation is selected, then an <br />angle must be entered for one or more of the reaches flowing into or out of a <br />junction. The momentum equation is set up to account for the angle of the <br />flow entering the junction. <br /> <br />Once you have all of the data entered for the junction, apply the data and close <br />the window by pressing the OK button. <br /> <br />Saving The Geometry Data <br /> <br />At this point in the example, all of the geometric data has been entered. <br />Before we continue with the example, you should save the geometric data to <br />the hard disk. Since the data has already been saved once, you simply have to <br />select Save Geometry Data from the File menu on the Geometric Data <br />window. We can now go on to enter the Steady Flow data. <br /> <br />Entering Steady Flow Data <br /> <br />The next step in developing the required data to perform steady flow water <br />surface profile calculations is to enter the steady flow data. To bring up the <br />steady flow data editor, select Steady Flow Data from the Edit menu on the <br />HEC-RAS main window. The Steady Flow Data editor should appear as <br />shown in Figure 4.8. <br /> <br />The first piece of data to enter is the number of profiles to be calculated. For <br />this example enter "3" as shown in Figure 4.8. The next step is to enter the <br />flow data. Flow data are entered from upstream to downstream for each <br />reach. At least one flow rate must be entered for every reach in the river <br />system. Once a flow value is entered at the upstream end of a reach, it is <br />assumed that the flow remains constant until another flow value is <br />encountered within the reach. Additional flow values can be entered at any <br />cross section location within a reach. <br /> <br />4-10 <br />