ENCN445-21S1 (C) Semester One 2021

Fluid Mechanics of Environmental Systems

15 points

Start Date: Monday, 22 February 2021
End Date: Sunday, 27 June 2021
Withdrawal Dates
Last Day to withdraw from this course:
  • Without financial penalty (full fee refund): Sunday, 7 March 2021
  • Without academic penalty (including no fee refund): Friday, 14 May 2021


Description and modelling of turbulence. Near and far field mixing behaviour. Dispersion in rivers, jets, plumes. Outfall design. Introduction to wave theory, including wave dispersion and forces.

Environmental fluid mechanics is a special branch of fluid mechanics associated with the interaction of humans with the naturally occurring fluid bodies – the atmosphere, the oceans, estuaries, rivers, and lakes/reservoirs. These fluid bodies impact on human civilisation in a number of critical ways:

 They present significant risk to humans through extreme events. The recent tsunami in Indonesia in 2004 and Japan in 2011 bear witness to the potential severity of this risk.
 They provide critical resources, namely water to drink, air to breathe and energy for power generation.

Human beings also impact on these fluid bodies:

 We modify these fluid bodies through man-made interventions. Drawing water from rivers for irrigation for example, or building a breakwater in a coastal zone.
 We use them for the disposal of our wastes. There are many instances of this, for example, ocean outfalls of municipal waste or effluent from desalination plants, smokestacks in the atmosphere and discharges from factories into rivers.

Environmental fluid dynamics is a very broad topic and this course can only provide a cursory introduction to it. However by the completion of the course you should appreciate some of the fundamental characteristics of these natural flows – in particular turbulence, wave motion, and convection– and you should be able to undertake basic modelling of certain aspects of our interactions with them – in particular the modelling of turbulent mixing in the ocean, rivers, atmosphere, and within buildings.

Learning Outcomes

This course is broken down into three sections, turbulence and far field mixing, coastal engineering, and jets and plumes. Each section comprises a set of modules with associated learning outcomes.

Turbulence and Far Field Mixing: (12 lectures + 4 tutorials) – Dr McConnochie
Module 1: Introduction to Turbulence (4 lectures)
Module 2: Turbulent Dispersion (5 lectures)
Module 3: Turbulence Modelling (3 lectures)

At the conclusion of the turbulence section you should be able to:

 Provide a qualitative description of turbulent flow that includes the ideas of a spectrum of eddies of varying sizes, the energy cascade and turbulent kinetic energy dissipation.
 Understand the basis of Reynolds averaging, why it is often required to make headway in solving turbulent flow problems, and the closure problem that results.
 Explain the concept of an eddy viscosity and describe two turbulence models, Mixing Length Theory and the k- model, that are based upon it.
 Understand how far field mixing can be modelled using the turbulent advection diffusion equation and be able to model such mixing using an appropriate model.

Coastal Engineering: (9 lectures + 3 tutorials) – Dr McConnochie
Module 1: Overview of Coastal Engineering (1 lecture)
Module 2: Wave Dynamics (3 lectures)
Module 3: Wave Transformations (3 lectures)
Module 4: Wave Impacts (2 lectures)

At the conclusion of the coastal engineering section you should be able to:

 Provide a broad overview of coastal engineering and explain some of the solutions, both hard and soft, that engineers employ to solve coastal engineering problems.
 Understand the basic behaviour of ocean waves, including dispersion and group and phase velocity.
 Understand the transformations that ocean waves undergo as they encounter the coast and be able to predict the result of this interaction.
 Analyse real wave data to obtain design wave parameters and analyse some of the impacts these waves may have on the coastal environment.

Jets and Plumes: (12 lectures + 7 tutorials) – Dr McConnochie
Module 1: Introduction (1 lecture)
Module 2: Jets (3 lectures)
Module 3: Plumes (4 lectures)
Module 4: Building Ventilation (4 lectures)

At the conclusion of the jets and plumes section you should be able to:

 Explain the important differences between jets, axisymmetric plumes, line plumes and wall plumes.
 Model the environment within a room and understand simple methods of natural ventilation.

Timetable 2021

Students must attend one activity from each section.

Lecture A
Activity Day Time Location Weeks
01 Monday 11:00 - 12:00 E16 Lecture Theatre
22 Feb - 4 Apr
3 May - 6 Jun
Lecture B
Activity Day Time Location Weeks
01 Tuesday 11:00 - 12:00 E16 Lecture Theatre
22 Feb - 4 Apr
26 Apr - 6 Jun
Lecture C
Activity Day Time Location Weeks
01 Wednesday 16:00 - 17:00 E6 Lecture Theatre
22 Feb - 4 Apr
26 Apr - 6 Jun
Tutorial A
Activity Day Time Location Weeks
01 Friday 12:00 - 13:00 Rehua 005
22 Feb - 28 Mar
26 Apr - 6 Jun

Timetable Note

The course is split into three essentially self-contained sections. The first introduces turbulent flow and discusses the problem of turbulent mixing in the environment when the environmental fluid is responsible for the transport and dilution of the effluent – this is known as far field mixing. The second considers one aspect of coastal engineering by providing an introduction to wave dynamics and the impact of ocean waves on the coastline. The third focuses on mixing in the near field where the environment plays a more minor role in the mixing process and the source discharge characteristics are predominant. It covers the canonical fluid flows referred to as jets and plumes as well as considering the flow and properties of air inside buildings.

Course Coordinator / Lecturer

Craig McConnochie


Assessment Due Date Percentage 
Exam 65%
Coastel Eng Project 10%
Jets and Plumes Project 15%
Turbulence Project 10%

The assessment for this paper will comprise two components – three projects and the final exam. The projects aim to provide you with the opportunity to work through substantial practical problems, putting into practice the analysis and design skills you have learnt. The final exam will focus more on the theoretical aspects of the course where the solution of complex practical problems is not possible due to the limited time available.

1. You cannot pass this course unless you achieve a mark of at least 40% in the final
exam. A student who narrowly fails to achieve 40% in the exam, may still may be eligible for a pass in the course if they have shown consistently high class attendance and have performed very well in the internal assessment items.
2.  All projects must be submitted by the due date. Late submissions will not be accepted. If a student is unable to complete and submit an assignment by the deadline due to personal circumstances beyond their control they should discuss this with the lecturer involved as soon as possible.
3.  Students in this course can apply for special consideration provided they have sat the final exam.
4.  All projects must be done individually."

Indicative Fees

Domestic fee $1,114.00

International fee $5,500.00

* All fees are inclusive of NZ GST or any equivalent overseas tax, and do not include any programme level discount or additional course-related expenses.

Minimum enrolments

This course will not be offered if fewer than 5 people apply to enrol.

For further information see Civil and Natural Resources Engineering .

All ENCN445 Occurrences

  • ENCN445-21S1 (C) Semester One 2021