Chapter 1. Flow in Open Channel

Slides:



Advertisements
Similar presentations
Chapter 3: Steady uniform flow in open channels
Advertisements

Chapter 13: Open Channel Flow
OPEN-CHANNEL FLOW Introduction Ch-10 of HH
Flood Profile Modeling with Split Flows and Weirs
Change of the flow state
Example: Uniform Flow at Known Q and y
Types of flow: Slide from Dr. Isaac.
End of Chapter 4 Movement of a Flood Wave and begin Chapter 7 Open Channel Flow, Manning’s Eqn. Overland Flow.
Design of Open Channels and Culverts
Open Channel Flow.
HYDRAULIC 1 CVE 303.
Open Channel Flow Part 2 (cont)
CHAPTER 6: Water Flow in Open Channels
Monroe L. Weber-Shirk S chool of Civil and Environmental Engineering Open Channel Flow June 12, 2015 
Open Channel Flow.
Pertemuan Open Channel 2. Bina Nusantara VARIED FLOW IN OPEN CHANNELS.
MECH 221 FLUID MECHANICS (Fall 06/07) Chapter 10: OPEN CHANNEL FLOWS
If there is no change in friction or slope as we move down stream
Open channel hydraulics
CE 1501 Selected Topic: Open Channel Flow Reading: Munson, et al., Chapter 10.
Monroe L. Weber-Shirk S chool of Civil and Environmental Engineering Open Channel Flow July 15, 2015 
FE Hydraulics/Fluid Mechanics Review
GRADUALLY VARIED FLOW CVE 341 – Water Resources
Water Flow in Open Channels
UNIFORM FLOW AND DESIGN OF CHANNELS
Open Channel Flow.
CH 7 - Open Channel Flow Brays Bayou Concrete Channel Uniform & Steady
PRINCIPLES OF OPEN CHANNEL FLOW
Hydraulic Routing in Rivers
Solution of the St Venant Equations / Shallow-Water equations of open channel flow Dr Andrew Sleigh School of Civil Engineering University of Leeds, UK.
Hydraulic Engineering
Hydraulics for Hydrographers Basic Hydrodynamics
The Stage-Discharge Rating D. Phil Turnipseed, P.E. Hydrologist USGS-FERC Streamgaging Seminar Washington, D.C. June 6-7, 2006.
Uniform Open Channel Flow
ERT 349 SOIL AND WATER ENGINEERING
Overview of Open Channel Flow Definition: Any flow with a free surface at atmospheric pressure Driven entirely by gravity Cross-section can vary with location.
CE 3372 Water Systems Design Open Conduit Hydraulics - II.
CE 3372 Water Systems Design
Basic Hydraulics: Channels Analysis and design – I
Open Channel Hydraulics
Basic Hydraulics: Open Channel Flow – I
OC FLOW: ENERGY CONCEPTS, CHANNEL ANALYSIS
DIMENSIONAL ANALYSIS SECTION 5.
Basic Hydrology & Hydraulics: DES 601 Module 16 Open Channel Flow - II.
OPEN CHANNEL FLOW  Any liquid flowing in a conduit or channel that is not completely filled and sealed (open to atmosphere) is considered an open channel.
6. Drainage basins and runoff mechanisms Drainage basins Drainage basins The vegetation factor The vegetation factor Sources of runoff Sources of runoff.
Properties of Open Channels  Free water surface Position of water surface can change in space and time  Many different types River, stream or creek;
Basic Hydraulics: Open Channel Flow – II
What is the Bradshaw model?
Open Channel Hydraulic
CE 3372 Water Systems Design
Chapter 11 Fluids.
Water Conveyance and Control
EXAMPLE Water flows uniformly in a 2m wide rectangular channel at a depth of 45cm. The channel slope is and n= Find the flow rate in cumecs.
UNIFORM FLOW AND DESIGN OF CHANNELS
Assoc. Prof. Dr. Tarkan Erdik
ERT 349 SOIL AND WATER ENGINEERING
Fluid Mechanics Dr. Mohsin Siddique Assistant Professor
Chapter 4. Analysis of Flows in Pipes
Uniform Open Channel Flow
Uniform Open Channel Flow – Ch 7
Chapter 4. Gradually-varied Flow
LECTURER: MADAM NOR AMANI FILZAH MOHD KAMIL
Open Channel Storm water Irrigation Waste water collection and treatment.
UH-Downtown White Oak Buffalo.
Introduction/Open-Channel Flow
Hydrodynamic Concepts
Fluvial Hydraulics CH-3
BAE 6333 – Fluvial Hydraulics
Types of Fluid Flows Prepared By : VINOD DAHIYA
Presentation transcript:

Chapter 1. Flow in Open Channel Learning Outcomes: Differentiate between open channel flow and pipe flow Define and explain on the types of flow Identify the state of flow and flow regimes Define open channel geometries

Chapter 1. Flow in Open Channel Stormwater Management and Road Tunnel (SMART), Kuala Lumpur, Malaysia Tahan river rapids Why do we need to learn open channel flow? Siberian meandering river

Figure. Sketch of open channel geometry Open channel flow is flow of a liquid in a conduit with a free surface subjected to atmospheric pressure. Free surface Flow Datum  x y u A B T Figure. Sketch of open channel geometry Definition Examples: flow of water in rivers, canals, partially full sewers and drains and flow of water over land.

Practical applications are the determination of: flow depth in rivers, canals and other conveyance conduits, changes in flow depth due to channel controls e.g. weirs, spillways, and gates, changes in river stage during floods, surface runoff from rainfall over land, optimal channel design, and others

1.1 Flow Parameters and Geometric Elements a. Depth of flow y is the vertical measure of water depth. Normal depth d is measured normal to the channel bottom. d = y cos  For most applications, d  y when   10%. cos 0.1 = 0.995. Free surface Flow Q Datum  x y d So = bottom slope Sw = water surface slope b. Flow or discharge Q is the volume of fluid passing a cross-section perpendicular to the direction of flow per unit time. Mean velocity V is the discharge divided by the cross-sectional area

A = cross sectional area covered by flowing water 1.1 Geometric Elements c. Wetted perimeter P is the length of channel perimeter that is wetted or covered by flowing water. T = top width y P A = cross sectional area covered by flowing water A B = bottom width

1.1 Geometric Elements d. Hydraulic radius R is the ratio of the flow area A to wetted perimeter P. e. Hydraulic depth D is the average depth of irregular cross section. B T A P y

Table. Open channel geometries Channel shape Area A Top width T Wetted perimeter P y B T Rectangular By B B + 2y y z T Triangular 1 zy2 2zy y z T Trapezoidal 1 B By + zy2 B + 2zy y T Circle  D  in radian  in angle  in radian

1.2 Types of Open Channel  Prismatic and non-prismatic channels Prismatic channel is the channel which cross-sectional shape, size and bottom slope are constant. Most of the man-made (artificial) channels are prismatic channels over long stretches. Examples of man-made channels are irrigation canal, flume, drainage ditches, roadside gutters, drop, chute, culvert and tunnel. All natural channels generally have varying cross-sections and therefore are non-prismatic. Examples of natural channels are tiny hillside rivulets, through brooks, streams, rivers and tidal estuaries.  Rigid and mobile boundary channels Rigid channels are channels with boundaries that is not deformable. Channel geometry and roughness are constant over time. Typical examples are lined canals, sewers and non-erodible unlined canals. Mobile boundary channels are channels with boundaries that undergo deformation due to the continuous process of erosion and deposition due to the flow. Examples are unlined man-made channels and natural rivers.

Terusan Wan Muhammad Saman, Kedah Canals - is usually a long and mild-sloped channel built in the ground, which may be unlined or lined with stoned masonry, concrete, cement, wood or bituminous material. Terusan Wan Muhammad Saman, Kedah Griboyedov Canal, St. Petersburg, Russia

Flumes - is a channel of wood, metal, concrete, or masonry, usually supported on or above the surface of the ground to carry water across a depression. This flume diverts water from White River, Washington to generate electricity Bull Run Hydroelectric Project diversion flume Open-channel flume in laboratory

Chute - is a channel having steep slopes. Natural chute (falls) on the left and man-made logging chute on the right on the Coulonge River, Quebec, Canada The spillway of Leasburg Diversion Dam is a vertical hard basin drop structure designed to dissipate energy Drop - is similar to a chute, but the change in elevation is within a short distance.

Stormwater sewer - is a drain or drain system designed to drain excess rain from paved streets, parkinglots, sidewalks and roofs. Storm drain receiving urban runoff Storm sewer

1.3 Types / Classification of Open Channel Flows Open channel flow conditions can be characterised with respect to space (uniform or non-uniform flows) and time (steady or unsteady flows). Space - how do the flow conditions change along the reach of an open channel system. a. Uniform flow - depth of flow is the same at every section of the flow dy/dx = 0 b. Non-uniform flow - depth of flow varies along the flow dy/dx  0 Time - how do the flow conditions change over time at a specific section in an open channel system. c. Steady flow - depth of flow does not change/ constant during the time interval under consideration dy/dt = 0 d. Unsteady flow - depth of flow changes with time dy/dt  0

1.3 Types / Classification of Open Channel Flows a. Uniform flow y Constant water depth b. Non-uniform flow y1 y2 Depth changes along the channel c. Steady flow y Time = t1 Time = t2 y1 Time = t1 Time = t2 d. Unsteady flow y t3 t2 t1 y t3 t2 t1

Gradually-varied flow Rapidly-varied flow Open channel flow Steady flow Unsteady flow Uniform flow Non-uniform flow Gradually-varied flow Rapidly-varied flow Various types of open-channel flow

The flow is rapidly varied if the depth changes abruptly over a comparatively short distance. Examples of rapidly varied flow (RVF) are hydraulic jump, hydraulic drop, flow over weir and flow under a sluice gate. The flow is gradually varied if the depth changes slowly over a comparatively long distance. Examples of gradually varied flow (GVF) are flow over a mild slope and the backing up of flow (backwater). RVF GVF RVF GVF RVF GVF RVF Sluice Hydraulic jump Flow over weir Hydraulic drop Contraction below the sluice

1.4 State of Flow The state or behaviour of open-channel flow is governed basically by the viscosity and gravity effects relative to the inertial forces of the flow. Effect of viscosity - depending on the effect of viscosity relative to inertial forces, the flow may be in laminar, turbulent, or transitional state. - Reynolds number represents the effect of viscosity relative to inertia, where V is the velocity, R is the hydraulic radius of a conduit and  is the kinematic viscosity (for water at 20C,  = 1.004  106 m2/s, dynamic viscosity  = 1.002  103 Ns/m2 and density  = 998.2 kg/m3). Re < 500 , the flow is laminar 500 < Re < 12500, the flow is transitional Re > 12500 , the flow is turbulent

Re < 500 , the flow is laminar 500 < Re < 12500, the flow is transitional Re > 12500 , the flow is turbulent The flow is laminar if the viscous forces are dominant relative to inertia. Viscosity will determine the flow behaviour. In laminar flow, water particles move in definite smooth paths. The flow is turbulent if the inertial forces are dominant than the viscous force. In turbulent flow, water particles move in irregular paths which are not smooth.

1.4 State of Flow Effect of gravity - depending on the effect of gravity forces relative to inertial forces, the flow may be subcritical, critical and supercritical. - Froude number represents the ratio of inertial forces to gravity forces, where V is the velocity, D is the hydraulic depth of a conduit and g is the gravity acceleration (g = 9.81 m/s2). Fr < 1 , the flow is in subcritical state Fr = 1 , the flow is in critical state Fr > 1 , the flow is in supercritical state

1.5 Regimes of Flow A combined effect of viscosity and gravity may produce any one of the following four regimes of flow in an open channel: a. subcritical - laminar , when Fr < 1 and Re < 500 b. supercritical - laminar , when Fr > 1 and Re < 500 c. supercritical - turbulent , when Fr > 1 and Re > 12500 d. subcritical - turbulent , when Fr < 1 and Re > 12500