BEng Civil Engineering

The behaviour of flows with a free surface affects the design of many civil engineering structures including weirs, spillways, man-made channels, coastal defences such as breakwaters and offshore structures such as pontoons, and platforms for oil & gas and renewable energy applications. This unit introduces the principles governing the behaviour of free-surface flows: specifically, open-channel flow and waves. Standard models are developed to model the main types of flow to predict surface level, velocities and pressures and to estimate structure loading.

The intended learning outcomes are focused on understanding the equations governing the behaviour of the different types of open channel flow and of wave motion so that these can be applied to practical engineering problems.

- To develop understanding of the fundamental principles that govern free-surface flows in open channels and waves.

- To apply these principles to predict flow depth and hydraulic transitions within open-channel flows and the characteristics and transformation of waves in offshore and coastal zones.

- To identify and employ relevant models to inform engineering design of structures subject to fluid flow in channels and at coastal locations.

Open Channel Flow

Introduction:

• Classification
• Normal flow
• Fluid head
• Froude number

Rapidly-varied flow

• Hydraulic jump
• Specific energy
• Critical-flow devices: broad-crested weir, venturi flume, sluice gate, free overfall
• Forces on objects

Gradually-varied flow

• Governing equations
• Profile classification and qualitative flow behaviour
• Numerical solution: standard-step method and direct-step method

Wave speed and analogy with compressible flow

• Long-wave speed on shallow water
• Zone of influence
• Analogy with compressible flow

Wave Mechanics

Linear wave theory for regular waves in arbitrary depth

• Wave parameters
• Governing equations
• Dispersion relationship
• Wave kinematics (velocity) and dynamics (pressure)
• Wave energy,  power and group velocity
• Deep- and shallow-water behaviour
• Interaction of waves with current

Nearshore wave transformations

• Refraction
• Shoaling
• Breaking
• Diffraction
• Reflection

Design Conditions

• Irregular-wave models and statistics
• Breakwater loading

Other - Assessed tutorial work

Exam - via script viewing

Tutorial work - feedback to cohort via lecture and blackboard. Individual feedback available as written comments on submitted work

Report - Feedback to cohort via lecture and blackboard. Individual feedback available as written comments on submitted work.