What Mesh Fineness to use for Pedestrian Wind Comfort PWC analysis
The Mesh Fineness for PWC analysis ranges from very coarse to very fine as a relative fineness that is based on 2 main things:
1- The Region of Interest ROI radius specified under ‘Region of Interest’ setting in the setup, this is used as a reference length for mesh sizing
2- The relative fineness level selected under mesh setting e.g ‘Moderate’
The calculation is as follows :
- The Minimum cell size in the mesh (within the ROI) depends on disk radius/Reference Length and fineness level
- It is calculated based on the following:
“Min cell size = Specified ROI radius / 100 * (Min reference cell size for selected fineness)”
E.g Minimum cell size for 300m ROI : 300/100 * 0.26 (moderate) = 3 * 0.26 = 0.78 m
Now How to know what should be the Minimum cell Size for the PWC study you wish to do ?
So based on the stage of the project i.e ‘Early stage design or Compliance level study’ you can decide the mesh fineness and the minimum cell size to achieve the accuracy required .
The Below Example is for a 300 m ROI size.
"Based on the London Wind Micro-Climate guidelines a compliance level Run must have :
- minumum cell size as 0.5 m with in the ROI
- and for smaller details e.g of Façade, entrances, balconies etc upto 0.3 m. "
The Minimum cell size is also displayed when a Simulation Run is created , see this article for more details…