LECTURER: MADAM NOR AMANI FILZAH MOHD KAMIL HYDRAULICS (BFC 21103) LECTURER: MADAM NOR AMANI FILZAH MOHD KAMIL ROOM: ST LEVEL 3, ROOM-PM 4 0137705583

Learning Objectives Knowing open stream classification and properties of fluid. Understanding the nature of the flow in an open channel. Understanding the definition of geometric elements in the calculation of open channel flow.

Learning Outcomes Making a comparison between open channel flow and flow in a pipe. Define and describe the types of flow. State flow conditions and flow regimes.

Syllabus 1.1 Introduction (slide 5) 1.2 State of Flow (slide 17) 1.3 Types of Open Channel Flow (slide 22) 1.4 Geometric Element of Open Channel (slide 31)

What is the significant of this subject to civil engineer? Introduction Hydraulic is related to the principle of fluid mechanics usage for structure of water engineering, civil and environmental engineering necessity especially hydraulic structure example channel, river, weir and water treatment plant What is the significant of this subject to civil engineer?

Introduction Properties of Fluid Detailed in fluid mechanics Relative Density Compressibility Capillarity Specific Gravity Density Bulk Modulus Viscosity Detailed in fluid mechanics

Introduction Open Channel Flow Flow in open channel has a free surface which is caused by atmosphere pressure Atmosphere Free surface Flow d Distributed flow Zo Datum

Introduction Open Channel Flow

Example: Constant flow in piping flow in time Steady Flow Flow in an open-channel is considered steady if the depth of flow (y) does not change and assumed to be constant during the time interval; dy / dt = 0. Example: Constant flow in piping flow in time

Steady Flow (Example)

Unsteady Flow Flow in an open-channel is considered unsteady if the water surface and depth of flow fluctuate from time to time. This means, dy / dt  0. Unsteady uniform flow is an impossible condition Example: flood

Uniform and Non-uniform Flow Flow is considered uniform if the depth of flow is the same at every section of the flow (dy/dx = 0). While, flow is considered non-uniform flow if the depth of flow varies at different sections of the flow (dy/dx  0). Non-uniform flow Uniform flow

Uniform and Non-uniform Flow Gradually varied flow (GVF) the depth changes gradually over a long distance along the length of a channel. Rapidly varied flow (RVF) the depth changes abruptly over a comparative short distance

Gradually varied flow (GVF) Example: backwater at the upstream of weir or sluice gate.

Rapidly varied flow (RVF) Example: hydraulic jump

Summary Open Channel Flow Steady Flow Uniform Flow Non-uniform GVF RVF Unsteady Flow GVUF RVUF

State of Flow Viscosity effect Gravity effect

Viscosity Effect Reynolds number depends on viscosity Fluid viscosity is constant Re < 500 - laminar 500 < Re < 12500 - transition Re > 12500 - turbulent

Laminar and Turbulent Flow Laminar flow Low velocity in small cross section channel. High viscosity. Turbulent Flow Deep of flow. Non-prismatic cross section (i.e; river) create the turbulent flow. Transition State of flow happen when laminar flow change to turbulent flow before alter to fully turbulent.

REYNOLDS EXPERIMENT Result Osborne Reynolds was the first scientist who had distinguished the type of flow by using a simple apparatus in 1883.

Gravity Effect State as inertia force to gravity force ratio and known as Froude number, Where; Fr = 1 – critical Fr < 1 – sub critical Fr > 1 – super critical

Sub critical laminar – Fr < 1.0, Re < 500 Flow Regime Combination of viscosity and gravity effect will create 4 state of regime which are; Sub critical laminar – Fr < 1.0, Re < 500 Super critical laminar – Fr > 1.0, Re < 500 Sub critical turbulent – Fr < 1.0, Re > 12500 Super critical turbulent – Fr > 1.0, Re > 12500

Type of Open Channel Natural channel Artificial channel

Natural channels are waterways that exist naturally on earth. Type of Open Channel Natural Channel Natural channels are waterways that exist naturally on earth. The properties of natural channels are normally very irregular and difficult to control. Examples: hillside rivulets, brooks, streams, rivers and tidal estuaries.

Type of Open Channel Artificial Channel Artificial channels are watercourses that are contracted and developed by human. The properties of artificial channels are based on developers’ requirements and controllable. Examples: floodways, irrigation canals, drainage ditches and spillways.

Artificial Channel In engineering practice, artificial channels are given different names such as: canal flume chute and drop sewerage

It is a long and mild-sloped channel built on the ground. Canal It is a long and mild-sloped channel built on the ground. Exist in earth surface or coated with concrete, cement, wood or others.

It is used in laboratory for research. Flume It is a hard channel or passage built from wood, metal or concrete across a depression. It is used in laboratory for research.

Chute is a steep-sloped channel. Chute and Drop Chute is a steep-sloped channel. Drop is similar to a chute, but the change in elevation takes place over a very short distance.

It is a closed conduit and built under soil surface. Sewerage It is a closed conduit and built under soil surface. The water is in half-fully flow.

TIME’S UP … THANK YOU Addition reading: Cengel Y. A. And Cimbala J.M. (2010). Fluid mechanics: Fundamentals and applications. McGraw-Hill. UK. Page 701 - 707 THANK YOU