Urban Microclimate and Vegetation

Wetting of building facades by wind driven rain

Wetting of building facades by wind-driven rain

Raindrop | Wind-driven rain | Film forming and runoff


Droplet impact on surfaces is an important phenomenon in various engineering applications. Droplet impact during wind-driven rain governs the wetting of building facades, a main factor of moisture damage of materials. To capture the phenomena of raindrop impact on porous materials, various imaging techniques and numerical simulation methods are used such as high-speed imaging, neutron and X-ray radiography, CFD and volume of fluid (VOF).

Raindrop captures Droplet captured by combination of methods.

Wind-driven rain

Accurate determination of surface wetting distribution is the first step towards moisture studies on building envelopes. Droplet impingement on fašades is influenced by the complex wind flow patterns around the buildings. Experimental and numerical wind-driven rain (WDR) studies have been conducted in a representative urban neighborhood. Turbulent dispersion of raindrops has been modeled using an Eulerian multiphase model for estimation of WDR.

Film forming and runoff

A 2D model of film forming and runoff as well as evaporation using finite volume discretisation and based on the compressible Navier-Stokes equation is developed. Numerical results have been validated against existing experimental results for film runoff on an inclined plate with relevant Reynolds number.

Modeling results on varying thickness of water film runoff

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