Seeking to find methods of reducing rain penetration problems in high-rise residential buildings and to increase the durability of building designs, Canada Mortgage and Housing Corporation has sponsored this research initiative into the modelling of wind-driven rain. Rain was simulated in the low speed test section of Boundary Layer Wind Tunnel II at the University of Western Ontario using an array of nine nozzles. Two phases of testing were conducted. The first was to study the effect of wind speed and wind angle on the wetting patterns for a "basic" building, with an exploratory look at the effect of surface features. The second phase was a study of the effect of building height and larger scale architectural features such as cornices and a peaked roof.

The "classic" wetting pattern was obtained on the windward face of a building in which the top corner is the wettest followed by the top and side edges. Local intensity factors in the top corners ranged from about 0.15 to 2.5 in the cases examined, with the corners being subjected to 2 to 50 times the rain impact as the central region of the face. The side wall remains relatively dry. For glancing wind angles, there can still be significant wetting along the top edge, upstream edge, and occasionally even the downstream edge for angles of 30, 45 and 60 degrees between the building face and the wind direction. Local intensity factors can increase fairly significantly with increasing wind speed. The general wetting pattern on a windward wall remains the same regardless of building height, although the intensity of wetting along the top edge likely increases with increasing height. Cornices and peaked roofs may reduce rain impact on the front face, while providing a good opportunity for drainage and therefore protection of the building face from surface migration.

• simulation: wind-driven rain
• wind driven rain : simulation of wind-driven rain and wetting pattern
• wind-driven rain: CFD models

1. An experimental study of pressure gradients and their implications for the design of pressure-moderated rainscreens
2. Optimum vent locations for partially-pressurized rainscreens
3. Understanding mold in the property restoration industry  

1. A study of mean pressure gradients, mean cavity pressures, and resulting residual mean pressures across a rainscreen for a representative building
2. An experimental study of pressure gradients and their implications for the design of pressure-moderated rainscreens
3. An exploratory study of the climatic relationships between rain and wind
4. BLWT, CFD and HAM modelling vs. the real world: bridging the gaps with full-scale measurements
5. Optimum vent locations for partially-pressurized rainscreens
6. Wind-driven rain study for the Governor's Road Project