Fluid Tunnel Research for Challenges of Urban Climate

TL;DR

This paper reviews experimental fluid tunnel methods for studying complex multiscale, multi-physics phenomena in urban climate, emphasizing recent advances, challenges, and guidelines for improving model accuracy and validation.

Contribution

It provides a comprehensive overview of fluid tunnel experimental techniques and discusses key challenges in modeling urban climate processes with multi-physics considerations.

Findings

Highlights the importance of high-quality measurements for model validation

Identifies three main challenges in urban climate modeling

Summarizes recent advances in experimental design for urban fluid dynamics

Abstract

Experimental investigations using wind and water tunnels have long been a staple of fluid mechanics research for a large number of applications. These experiments often single out a specific physical process to be investigated, while studies involving multiscale and multi-physics processes are rare due to the difficulty and complexity in the experimental setup. In the era of climate change, there is an increasing interest in innovative experimental studies in which fluid (wind and water) tunnels are employed for modelling multiscale, multi-physics phenomena of the urban climate. High-quality fluid tunnel measurements of urban-physics related phenomena are also much needed to facilitate the development and validation of advanced multi-physics numerical models. As a repository of knowledge in modelling these urban processes, we cover fundamentals, recommendations and guidelines for experimental design, recent advances and outlook on eight selected research areas, including (i) thermal buoyancy effects of urban airflows, (ii) aerodynamic and thermal effects of vegetation, (iii) radiative and convective heat fluxes over urban materials, (iv) influence of thermal stratification on land-atmosphere interactions, (v) pollutant dispersion, (vi) indoor and outdoor natural ventilation, (vii) wind thermal comfort, and (viii) urban winds over complex urban sites. Further, three main challenges, i.e., modelling of multi-physics, modelling of anthropogenic processes, and combined use of fluid tunnels, scaled outdoor and field measurements for urban climate studies, are discussed.