Glenn E. Moglen Department of Civil & Environmental Engineering Virginia Tech End-of-semester wrap-up CEE 4324/5984 –Open Channel Flow – Lecture 27

Questions from Lecture 26? Final Exam will be Monday, December 12 from 1:05pm to 3:05pm (same rooms as usual). One page (front & back) study sheet Calculator (no computers) HEC-RAS Contrast with Standard Step Method Questions? Questions on Last Year’s Final? “Homework 10” Review Please fill out course evaluation Final Comments Today’s Agenda:

Conjugate Curve Concept Figure from Henderson (1966).

HEC-RAS HEC-RAS (Hydrologic Engineering Center-River Analysis System) is the industry standard program for calculating water surface profiles.

HEC-RAS - Input Input is divided into three categories Specifying cross-section and reach geometry Cross-section shape, left/right bank identification, channel and bank roughness Resolution (spacing between x-sections) Specifying flows conditions Discharge values Boundary conditions Specifying analysis “plan” (supercritical, subcritical or “mixed” flow)

HEC-RAS - Output Output is both graphical and tabular Graphical output Allows visualization of cross-sections and surface water profiles Allows visualization of a range of state variables (e.g. velocity, hydraulic radius, depth) as a function of position in the channel Tabular output Several standard tables pre-defined Ability to create custom tables of state variables

HEC-RAS – Overall Control Panel Edit Geometry Specify/Run Analysis Plan Specify Flow Conditions View Graphical Output View Tabular Output

HEC-RAS – Input: Geometry Plan view of system Cross-section editor

HEC-RAS – Input: Flow Conditions Specify Boundary Conditions Specify Discharges

HEC-RAS – Input: Analysis Plan Not much to it… Choose flow regime

HEC-RAS – Output: Graphical Profile Plot General Profile Plot

HEC-RAS – Output: Tabular Summary Output Table by Profile This column added using Options: Define Table…

HEC-RAS – Contrast to Standard Step Method Standard Step Method – Strengths Quick to use (once you have a template) Tabular format gives physical insight Useful if “x” location of certain key depths are desired HEC-RAS – Strengths Is “industry standard” software Calculates composite profiles all at once Allows variable cross-section, roughness, slope, discharge, etc. Has nice visualization tools Useful if “y” value at certain key “x” locations are desired

Questions from Practice Final Exam?

“Homework 10”: Full Profiles… Profile Beginning Depth (ft.) Ending Depth (ft.) Length (ft.) S2S (critical)1.81 (normal)301 S1S (conjugate to normal) 3.52 (alternate to gate opening) 31 S3S3 1.6 (gate opening 1.81 (normal)204

“Homework 10”: Limited to 60 ft. S 1 grows to 40 feet (was 31 feet) S 2 shrinks to 20 feet (was 301 feet)

Please fill out course evaluation I do review the course evaluation and especially make use of comments both positive and negative. I appreciate your thoughts and feedback. Thank you!

Final Comments… Test is comprehensive, but emphasis is on qualitative (and a little quantitative) surface water profiles. Single, 8.5x11 “study sheet” (both sides) allowed. No worked examples. Focus on concepts and have a solution strategy in mind. Don’t just start writing equations and calculating w/o a plan. It all comes back to fluency with gates, steps, and constrictions on an E-y diagram. If time is an issue, tell me your strategy. Thank you – it has been a pleasure.