Analyzing wind-driven rain on a building facade using the laser precipitation monitor (LPM)

This paper is concerned with a building situated in the west of Scotland which faces severe weather conditions with high wind speeds and driving rain occurring frequently. This results in extensive damage to the building fabric, and affects the internal climate which leads to a serious issue in building construction. In this study, a three-dimensional numerical model of airflow around the building is investigated. This investigation is part of ongoing research on wind-driven rain which has established the importance of moisture stresses, wind flow and rain impacts on a commercial building. The full scale experimental facility which includes anemometers, rain gauge, driving rain gauges and sensors is described. To supplement this, a sophisticated laser precipitation monitor (disdrometer) was installed, which collects rain data every 1-minute. This provides accurate measurement of drop size and speed of the falling raindrops which plays an important role in wind-driven rain studies. Comparisons with numerical simulations and experimental data were predicted. Results shows that the average predominantly wind direction for the sample test period is from south-west (223° from north) and the driving rain during this period is 86.8 mm for the west facing façade and 193.4 mm for the south facade. From the computational fluid dynamics (CFD) simulations, it is predicted that the change in velocity profile along the laser strip is due to the test building and the disdrometer head itself, which ultimately affects the driving rain calculations.