1. Complete all tasks as instructed with the assignment question sheet
2. Submit both the report (as Part 1) and zipped MIKE21 files (as Part 2) electronically to the “Submission: Assignment 2 – Wave Modelling, Due on May 27, 2019” link on Learning@Griffith
The Moreton Bay is on the eastern coast of Australia, 14 km from central Brisbane, which is classified as the most important coastal resources zone in Queensland. The Brisbane River is about 344 km, the longest river in southeast Queensland. The Port of Brisbane coordinates large traffic along the shipping channel which crosses the northern section of the bay. It is currently under a large upgrade and extension. Accurate predictions of wave climate are essential when determining design data for marine structure.
Figure 0: Brisbane River and Moreton Bay. ( http://www.ga.gov.au/mapconnect/ )
· The study area of Moreton Bay’s geographical position of origin is 27.5255S and153.0364E (Easting 503202.6966424, Northing 6954863.894501). The bathymetry data is in the pre-generated file of “Moreton_Bathy.mesh”.
· The domain has Northern, Southern and Eastern and Brisbane river mouth open boundaries.
· A MIKE 21 SW model has been developed and calibrated using the Moreton Buoy data (Easting 519719, Northing 6985769). The following model parameters will be applied:
· Basic equations: Fully spectral formulation and Instationary formulation
· Spectral discretization: 25 frequencies and 16 directions
· Diffraction needs to be considered with smoothing factor and steps are 1 for both
· Include quadruplet wave interaction
· Constant wave braking index of 0.8
· D50 sand size is 0.0002 m
· No whitecapping
· The Port Brisbane is located at (Easting 520000, Northing 6973000).
· Rose of wind direction versus wind speed information in four seasons is provided in the file “040223- 3pm-all.pdf”. See www.bom.gov.au/climate/averages/wind/wind_rose.shtml to interpret the data.
· Determine three prevailing/predominant wind directions and their corresponding wind speeds and predict the fully developed wave parameters under these 3 wind conditions.
Your engineering company has been approached by to predict the design wave conditions by using MIKE 21 SW. You should work individually and complete the requested tasks:
1. Prepare and Pre-process required data
2. Establish a spectral wave model using the provided calibrated model parameters detailed above
3. Complete simulations with 3 scenarios – the most influential wind conditions
4. Analyse results including (i) the wave height/direction and period distributions in the whole domain (bay) (ii) the wave characteristics (wave height, wave period, wave direction and wave spectrum) at the Port of Brisbane
5. Complete a report
The report must include:
· Introduction: Introduce the project and identify the objectives of the study. Introduce the model briefly, and give the key model parameters applied.
· Results: Display the simulation results in a clear and appropriate manner, i.e. all figure axes and table columns must be properly labelled with the correct units, captions and brief explanation are required for all figures.
· Discussion and conclusion: A brief analysis that summarises the data and draws some conclusions.
Across Australia, wind speed and wind direction measurements are made at various times of the day. Historically, these measurements tended to occur at 9am and 3pm, although some locations (mostly sites within cities and at airports) had more extensive observation programs. More recently, the introduction of Australia’s Automatic Weather Station (AWS) network has allowed the frequency of observations to increase, in many cases to eight or more observations per day.
Wind roses summarise the occurrence of winds at a location, showing their strength, direction and frequency. The wind roses available on this web site are based on at least 15 years of records, and have been created for the more common 9am and 3pm observation times.
Interpreting the wind rose
There are a number of different formats which can be used to display wind roses. These wind roses have been constructed in the following way:
· The percentage of calm conditions is represented by the size of the centre circle – the bigger the circle, the higher is the frequency of calm conditions.
· Each branch of the rose represents wind coming from that direction, with north to the top of the diagram. Eight directions are used.
· The branches are divided into segments of different thickness and colour, which represent wind speed ranges from that direction. Speed ranges of 10km/h are used in these wind roses. The length of each segment within
a branch is proportional to the frequency of winds blowing within the corresponding range of speeds from that direction.