Wind-driven rain as a boundary condition for HAM simulations: Analysis of simplified modelling approaches

Impact of wind-driven rain on historic brick wall buildings in a moderately cold and humid climate: Numerical analyses of mould growth risk, indoor climate and energy consumption

“…When the wind is oblique to the facade, the cosine projection method [11] was adopted for the calculation of the catch ratio. When the angle  between the normal to the facade and the wind direction is obtuse, the catch ratio on that facade is assumed zero.…”

“…Note however that the cosine projection method is less reliable when the angle  gets close to 90 degree [26]; but, because the catch ratio is very low for such angles, the error is of low importance from the point of view of heat and moisture transfer simulation in building components [11]. WDR intensities at the exterior wall surfaces with an interval of 0.2 m were calculated by combining the hourly climate data and the catch ratio data determined above (the catch ratio data at the edge and the centre on the facade are shown in Fig.…”

“…In reality, these values depend on wind speed, wind direction and position on the facade, and they may have a significant influence on the moisture response [11]. For instance a larger value is expected at the edge of the wall compared to the centre of the wall when the main stream of the wind is facing the facade.…”

“…Janssen et al [4,11] and Blocken et al [12] recently formulated the implementation of numerically determined WDR loads as boundary condition in the heat and moisture transfer analysis in building enclosures, based on advanced numerical techniques of Computational Fluid Dynamics (CFD) [13,14]. Also Häupl et al [15] numerically investigated the impact of the rain on the hygrothermal performance of the facade of the 'Rijksmuseum' in Amsterdam, the Netherlands.…”

Convective heat transfer coefficients for exterior building surfaces: Existing correlations and CFD modelling

“…Often, information on CHTCs is used to determine convective moisture transfer coefficients (CMTCs), by using the Chilton-Colburn analogy. Both CHTCs and CMTCs have an impact on the heat and moisture transport in the building envelope, and they are required for example to assess drying of facades, wetted by wind-driven rain [1,2] or by surface condensation by undercooling during clear cold nights [3,4]. This hygrothermal behaviour within the envelope and at the exterior surface is important for several physical, chemical and biological weathering processes such as microbiological vegetation (algae) and mould growth, reaction of deposited pollutants on the wetted surface, freeze-thaw degradation, salt transport, crystallisation and related deterioration, etc.…”