Numerical modeling of turbulent dispersion for wind-driven rain on building facades

Kubilay, Aytaç; Derome, Dominique; Blocken, Bje Bert; Carmeliet, JE Jan

doi:10.1007/s10652-014-9363-2

Cited by 41 publications

(33 citation statements)

References 55 publications

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“…Lagrangian particle tracking (LPT) models, combined with the steady Reynolds-averaged Navier-Stokes (RANS) equations, are the most commonly used method in the literature to estimate WDR intensity (Choi 1993;Lakehal et al 1995;Hangan 1999;Etyemezian et al 2000;Blocken and Carmeliet 2002;van Mook 2002;Blocken andCarmeliet 2006a, 2007b;Briggen et al 2009;Abuku et al 2009a;van Hooff et al 2011;Foroushani et al 2014). One alternative to the LPT models is the Eulerian multiphase (EM) model (Huang and Li 2012;Kubilay et al 2013), which can also be used to model the turbulent dispersion of raindrops with ease for time-averaged WDR calculations (Kubilay et al 2015a). In the EM model, the rain is regarded a continuum, so similar to the gas phase, i.e.…”

Section: Question 1: What Is the Relevance And Significance Of Wdr Inmentioning

confidence: 99%

“…Furthermore, as the fluctuations superimposed on the mean wind velocity are stochastic, this approach requires a large number of simulation runs to get the correct WDR intensity distribution on the facade. On the other hand, Kubilay et al (2015a) model the turbulent transport of raindrops with a more direct approach using the EM model. The resulting turbulent term in the momentum equation for the rain phases is expressed based on a response coefficient.…”

Section: Question 4: Does Turbulence Play An Important Role?mentioning

confidence: 99%

“…Fig. 5 compares the catch ratio charts with and without turbulent dispersion of raindrops at different positions on the windward facade of a high-rise building (Kubilay et al 2015a). Ignoring turbulent dispersion leads to errors as high as 75% at high wind speed and low rain intensity, with average errors of 8%, 45%, 57%, 64% respectively for each position on Fig.…”

Section: Question 4: Does Turbulence Play An Important Role?mentioning

confidence: 99%

“…5.The influence of turbulent dispersion is more pronounced for low reference rainfall intensity and high reference wind speed values, and relatively more pronounced at lower parts of the facade. The model is validated using measurements on a monumental tower building, where the discrepancy between the numerical and measured values decreases considerably at the lower parts of the tower by modeling the turbulent dispersion of raindrops (Kubilay et al 2015a). …”

Section: Question 4: Does Turbulence Play An Important Role?mentioning

confidence: 99%

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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 1: What Is the Relevance And Significance Of Wdr Inmentioning

confidence: 99%

Section: Question 4: Does Turbulence Play An Important Role?mentioning

confidence: 99%

Section: Question 4: Does Turbulence Play An Important Role?mentioning

confidence: 99%

Section: Question 4: Does Turbulence Play An Important Role?mentioning

confidence: 99%

See 2 more Smart Citations

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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show abstract

“…The study involves 18 WDR gauges with an acquisition resolution of about 0.025 mm/tip that aim to measure and compare the spatial and temporal distribution of WDR intensity on the facades of the two buildings. Furthermore, the field measurement data are used to validate CFD simulations of WDR which are performed with an Eulerian multiphase (EM) model that takes into account the turbulent dispersion modeling of raindrops [32]. In the present paper, section 2 presents the field measurement geometry and the measured rain event data for the validation study.…”

Section: Accepted For Publication In Journal Of Wind Engineering and mentioning

confidence: 99%

Wind-driven rain on two parallel wide buildings: Field measurements and CFD simulations

Kubilay

Derome

Blocken

et al. 2015

Journal of Wind Engineering and Industrial Aerodynamics

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Most studies of wind-driven rain (WDR) reported in the literature focus either on isolated buildings or on a particular building in geometrically complex environments. There is a need for experimental and numerical studies for more generic multi-building geometries. The present study reports detailed field measurements and numerical simulations of WDR that are conducted for an idealized geometry with two parallel wide buildings with different heights, located in Dübendorf, Switzerland. The datasets of rain events and WDR measurements with high spatial and temporal resolution are made available online to download and are intended for model development and validation. Numerical simulations are performed with computational fluid dynamics (CFD) based on the 3D steady Reynolds-averaged Navier-Stokes (RANS) equations and an Eulerian multiphase (EM) model for WDR, including the turbulent dispersion of raindrops. The numerical results are validated by comparing the calculated catch ratio values and cumulative WDR amounts with data from the field measurements. The CFD simulations accurately estimate the WDR intensities at the positions of 18 WDR gauges. The average discrepancies between the numerical and experimental results are found to be 6.9% for the rain event on February 20-21, 2014 and 4.9% for the rain event on August 2-3, 2014. In different building configurations, the influences of recirculation regions, sheltering, wind-blocking effect and acceleration of wind determine the WDR distribution on the downstream building. WDR can increase due to recirculation regions and acceleration of wind, while wind-blocking effect and sheltering decrease WDR.

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In Situ Methodology to Assess the Action of Water-Wind on Building Windows

Carretero-Ayuso

Bienvenido-Huertas

Rodríguez-Jiménez

2022

Lecture Notes in Civil Engineering

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The chapter describes a new methodology for the evaluation of the in situ water tightness in window openings located in the building envelope, as well as the development process carried out for its real application. It is an innovative non-destructive testing procedure that reproduces the effects of rain combined with wind, which is applicable both during the building construction process and in buildings in use. It is a useful tool for tightness analysis in quality control of elements and constructive pathologies that offers verifiable results in the field of habitability evaluation in buildings.

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Numerical modeling of turbulent dispersion for wind-driven rain on building facades

Cited by 41 publications

References 55 publications

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

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

Wind-driven rain on two parallel wide buildings: Field measurements and CFD simulations

In Situ Methodology to Assess the Action of Water-Wind on Building Windows

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