CFD modelling, Gold Coast, Australia


On 25 March 2017, a tropical low in the Coral Sea developed into Tropical Cyclone (TC) Debbie, and tracked south along the Queensland coast. It made landfall as a category 4 Severe Tropical Cyclone at Arlie Beach around 12:40 on 28 March 2017.

Analysis estimates the magnitude to be a 1 in 300-year R.P. event. Severe damage was observed and we were asked if our Flow3D model would reproduce this.


Using Flow3D, a Computational Fluid Dynamics (CFD) model, we now have the capability to model the river bed/floodplain deforming (entraining and depositing bed material) due to scour which enabled us to predict a scour depth and location. We ran the model and found when looking at the water surface and velocities the water overtopped the 12m high road bridge and the road.

Modelled scour depths and locations demonstrated that the structure was at risk in the areas known to have failed. Once the model showed undermining of the bridge embankment, the model was stopped as the structure was clearly at risk. The modelled scour locations and depths demonstrated a high level of correlation with the observed scour.


This modelling approach can be used to identify at risk structures and can also provide targeted information as to where scour protection is most needed. Cost savings are therefore achievable, as the whole structure may not require the same level of protection at all locations.

CFD modelling is used for many things but our focus is water based civil infrastructure, providing increased levels of certainty for environmental and engineering projects. Software costs and model run times have reduced significantly, so much so that they are often more cost-effective solutions than 2D models.

Want to know more?

Email Andrew Collier for more information on CFD modelling. You can also find out more on our flood and water management web pages.

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