Moisture response of building facades to wind-driven rain: Field measurements compared with numerical simulations

Abuku, Masaru; Blocken, Bje Bert; Roels, Staf

doi:10.1016/j.jweia.2009.06.006

Cited by 42 publications

(30 citation statements)

References 30 publications

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“…The contact area of droplets impacting with an impact angle is elongated along the projected direction of the impact velocity and the length of contact area is traditionally estimated using the cosine of the impact angle (Laan et al 2015). This approach is used for water droplet impingement on a brick in Abuku et al (2009c).…”

Section: Question 7: How Do Rain Droplets Interact With Porous Materimentioning

confidence: 99%

Ten questions concerning modeling of wind-driven rain in the built environment

Derome

Kubilay

Defraeye

et al. 2017

Building and Environment

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Wind-driven rain (WDR) in the built environment is a complex multiscale phenomenon. Wind flows in complex urban environment and rain events of various intensities may lead to very different rain deposition distributions within the city. Proper modelling of WDR is required as moisture is a main cause of material degradation in the built environment but also as understanding the water cycle in the urban environment is essential to provide solutions for the urban heat island, amongst others. What are the main aspects to be taken into account to predict wind-driven rain? How should such aspects be considered and modeled? Is it possible and relevant to predict in detail the moisture loads due to rain in complex systems as cities? This paper answers these questions from a multiscale perspective combining modeling and experimental work. The different scales relevant for accurate estimation of wind-driven rain in the built environment are presented. Rain deposition on complex geometries can be modeled by CFD, taking into account turbulent dispersion. Such modeling provides the impact velocity and angle of attack for each droplet size at any location on the urban surfaces. Using this information and the structure of the surface, the fate of the rain droplets can be predicted, namely whether it splashes, bounces or simple spreads. KeywordsWind-driven rain, built environment, droplet trajectory, computational fluid dynamics (CFD), WDR catch ratio, droplet fate, porous materials Introduction Rain in the built environment is a complex phenomenon which has impact on, amongst others, durability of the materials, vitality of urban vegetation, management of storm water and comfort, safety and health of the population. Not only does rain induce an environmental load on the surfaces it impacts, but, contrary to the other environmental loads of solar radiation and wind flow, a large part of the rain water remains present after the rain event and such presence must be accounted for despite the fleeting and stochastic nature of liquid flow. To properly capture rain, the different time scales of the phenomenon need to be considered. The first time scale is the few minutes rain droplets spend in the air before deposition. Air flow is drastically affected by the presence of buildings, influencing the distribution of rain load in the built environment. Then, the few milliseconds when droplets impact surfaces explain the different outcomes of spreading, splashing and/or rebound. The settlement of droplets on surfaces takes minutes, and the wetting of the surface and absorption in the porous media take several hours. In addition, as more and more droplets rest on a surface, they may coalesce and form a water film, resulting in rivulets and film run-off on the different surfaces. After a rain event, evaporation of the droplets and drying of the materials can take hours to days. As such rain deposition and the ensuing fate, i.e. the succession of subjected phenomena, of water is a multifaceted phenomenon which can be appropriately mo...

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Section: Question 7: How Do Rain Droplets Interact With Porous Materimentioning

confidence: 99%

Ten questions concerning modeling of wind-driven rain in the built environment

Derome

Kubilay

Defraeye

et al. 2017

Building and Environment

View full text Add to dashboard Cite

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“…The results have been compared against computer simulations with the software BSim2000 [115]. The moisture response of building façades to wind-driven rain is investigated by Abuku et al [116] at the VLIET test facility. The experimental set-up collected data on the relevant meteorological parameters, the impinging wind driven rain intensity, and the resulting material weight change of a calcium silicate building material sample.…”

Section: Performance Assessment Of Building Componentsmentioning

confidence: 99%

Outdoor test cells for building envelope experimental characterisation – A literature review

Cattarin

Causone

Kindinis³

et al. 2016

Renewable and Sustainable Energy Reviews

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In the past decades the construction sector experienced the diffusion of a wide variety of complex building envelope components and passive elements and strategies, characterized by a dynamic response to the climatic parameters. Many of these components have been claimed to contribute to reducing building energy use and improving occupants' comfort. These kind of envelope elements need nevertheless to be tested under laboratory and real dynamic weather conditions in order to characterise, and possibly to model, their behaviour and their effectiveness both in terms of energy saving and indoor environmental quality. Both indoor laboratories and outdoor test cells have been developed in order to tackle the challenging issue of experimentally characterising innovative envelope elements. However, not always the experimental methodologies are fully and explicitly described in the available literature, and they are rarely compared to other types of experimental procedures. The aim of the present paper is to describe and review recent state of the art technologies for outdoor test cells. The paper starts with a short introduction on potentialities and limitations of outdoor facilities with respect to indoor laboratories and real buildings field tests, and it continues with a detailed classification and description of the most relevant outdoor test cells developed in recent years.

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“…Moreover the pressure drops across the NE and SW wall together with the air velocity in the ventilation duct are measured. Outside conditions are logged with a weather station and meteorological mast [18].…”

Section: Test Setupmentioning

confidence: 99%