Abstract
Complex flow and pollutant dispersion simulations in real urban settings were investigated by using computational fluid dynamics (CFD) simulations with the SST k−ω Reynolds-averaged Navier–Stokes (RANS) equation with OpenFOAM. The model was validated with a wind-tunnel experiment using two surface-mounted cubes in tandem, and the flow features were reproduced with the correct qualitative behaviour. The real urban geometry of the Parade Square in Warsaw, Poland was represented with both laser-scanning data for the ground geometry and the CityGML standard to describe the buildings as an example. The Eulerian dispersion of a passive scalar and the flow behaviour could be resolved within minutes over a computational domain with a size of 958 × 758 m2 and a height of 300 m with over 2 M cells due to the good and strong parallel scalability in OpenFOAM. This implies that RANS modelling with parallel computing in OpenFOAM can potentially be used as a tool for situational awareness on a local urban scale; however, entire cities would be too large.
Highlights
The simulation of intended or unintended atmospheric dispersion in a complex geometry—e.g., in an urban area or industrial site—is necessary for the assessment of hazards
Wind-field modelling is imperative for such capabilities, and computational fluid dynamics (CFD) models have gained increased popularity for phenomena occurring at the street level, such as wind wakes and re-circulation patterns, as people who are at risk can be modelled
The Reynolds-averaged Navier–Stokes (RANS) model is the fastest and is, likely a suitable choice for moderately large areas [1]. It involves solving the general equations of fluid dynamics together with a turbulence closure in order to approximate the turbulent behaviour of the flow
Summary
The simulation of intended or unintended atmospheric dispersion in a complex geometry—e.g., in an urban area or industrial site—is necessary for the assessment of hazards. Wind-field modelling is imperative for such capabilities, and computational fluid dynamics (CFD) models have gained increased popularity for phenomena occurring at the street level, such as wind wakes and re-circulation patterns, as people who are at risk can be modelled. Among these models, the Reynolds-averaged Navier–Stokes (RANS) model is the fastest and is, likely a suitable choice for moderately large areas [1]. The question of the size of the domain that can be modelled with RANS within the timeframe of a first response remains
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