HY8:Polynomial Generation: Difference between revisions

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Inlet control means that flow within the culvert barrel is supercritical and not capable of transmitting losses upstream.  The determination of the headwater depth, therefore, is not found using the energy equation, but is the result of many scaled model tests.  In HDS-5 (Normann et al. 2001), submerged and unsubmerged equations developed by the National Bureau of Standards from the scaled model tests were originally used to determine headwater depths.  These equations required four coefficients, K, M, c, and Y.  Unfortunately, once plotted, the transition zone between unsubmerged and submerged flow was not well defined.  For the purposes of the HY-8 program, a fifth degree polynomial curve was fitted through the three regions of flow: unsubmerged, transition, and submerged (see equation below).  Fifth degree polynomial coefficients were obtained for all combinations of culvert shape and inlet configurations.   
Inlet control means that flow within the culvert barrel is supercritical and not capable of transmitting losses upstream.  The determination of the headwater depth, therefore, is not found using the energy equation, but is the result of many scaled model tests.  In HDS-5 (Appendix A), submerged and unsubmerged equations developed by the National Bureau of Standards from the scaled model tests were originally used to determine headwater depths.  These equations required four coefficients, K, M, c, and Y.  Unfortunately, once plotted, the transition zone between unsubmerged and submerged flow was not well defined.  For the purposes of the HY-8 program, a fifth degree polynomial curve was fitted through the three regions of flow: unsubmerged, transition, and submerged (see equation below).  Fifth degree polynomial coefficients were obtained for all combinations of culvert shape and inlet configurations.   


   
   

Revision as of 01:02, 16 December 2011

Inlet control means that flow within the culvert barrel is supercritical and not capable of transmitting losses upstream. The determination of the headwater depth, therefore, is not found using the energy equation, but is the result of many scaled model tests. In HDS-5 (Appendix A), submerged and unsubmerged equations developed by the National Bureau of Standards from the scaled model tests were originally used to determine headwater depths. These equations required four coefficients, K, M, c, and Y. Unfortunately, once plotted, the transition zone between unsubmerged and submerged flow was not well defined. For the purposes of the HY-8 program, a fifth degree polynomial curve was fitted through the three regions of flow: unsubmerged, transition, and submerged (see equation below). Fifth degree polynomial coefficients were obtained for all combinations of culvert shape and inlet configurations.


File:HY8Polynomial Equation.jpg


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HY-8
Introduction:Getting Started   •   Layout   •   Vena Contracta   •   Building a Project   •   Locate Project   •   Culvert Crossing Data   •   Run Analysis   •   Report Generation
Crossing and Culvert Data:Crossings   •   Discharge Data   •   Roadway Data   •   Tailwater Data   •   Irregular Channel   •   Culvert Data   •   Site Data   •   Culvert Invert Data   •   Embankment Toe Data
AnalysisProject Units   •   Roadway Overtopping   •   Inlet Control Computations   •   Outlet Control Computations   •   Tables and Plots
Energy DissipationScour Hole Geometry   •   Increased Resistance   •   Tumbling Flow   •   USBR Type IX Baffled Apron   •   Drop Structures   •   Stilling Basins   •   Streambed Level Structures
MethodsAquatic Organism Passage   •   Low Flow Hydraulics
TroubleshootingDifferences from DOS HY-8   •   Limitations   •   HY-8 User Manual
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