Knowing which way the wind blows – using CFD for Pedestrian Comfort & Safety
January 17th, 2020
We are increasingly asked by those involved in planning and building decisions to use CFD to support or replace desktop studies and wind tunnel tests.
The importance of producing a safe and pleasant environment to buildings is increasing, and wind engineers are often asked to look over designs when they are in the formative stage and before significant changes are finalised (e.g. orientation, gaps with surroundings buildings, landscaping, canopies, etc).
The emphasis of a wind microclimate study is people and the effects of wind on them. Two aspects must be examined separately, their comfort and their safety. Each of them requires its own set of criteria.
When it comes down to microclimate studies, meteorological data and consideration of terrain are needed first to obtain features of the wind profiles approaching the site
Then we run a series of simulations with ANSYS CFD to obtain the flow patterns within and around the proposed development for the wind in different directions. We combine these results with the wind frequency data to evaluate the suitability of specific locations on and around the site for particular activities against the well-known Lawson criteria.
Our clients are finding CFD a useful alternative to wind tunnel tests as it allows them to visualise variables throughout the whole study domain. It is also often cheaper and quicker to carry out, particularly if alternatives are considered. Geometry models can be modified quickly for multiple simulations.
The biggest challenge we currently find is receiving acceptable quality geometry that can be quickly meshed. Although we can fix CAD problems ourselves with tools such as SpaceClaim, we are working with our clients to create better models at source to save time and money.
Hopefully, with the increase in awareness and use of BIM within the industry, this issue will one day blow away!
For more information about ANSYS CFD simulation software, please click here >>
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