Assessing wind comfort in urban planning

There are increasing concerns regarding the quality of urban public spaces. Wind is one important environmental factor that influences pedestrians’ comfort and safety. In modern cities, there are more and more high constructions and complex forms which can involve significant problems of wind discomfort around these buildings. Today, architects and town planners need guidelines and simple design tools to take account of wind in their projects. This paper addresses the progress made towards computational fluid dynamics (CFD) simulations for assessing wind comfort in urban planning. We validated Fluent software for wind studies in urban environments by comparing our simulations results with wind tunnel tests. This validation shows that wind mean velocities around buildings can be simulated numerically with a very high degree of accuracy. Based on the results of a great number of CFD simulations, we developed a methodology and simple graphical tools to quantify critical wind speeds around buildings. This article should thus help in practice architects and town planners to design our built environment. Moreover, this paper shows how numerical modeling is now a high-performance tool to work out useful guidelines and simple design tools for urban planners

Wind-induced vibrations of structures : with special reference to tall building aerodynamics

This chapter examines the wind-induced vibrations of buildings and structures. In particular, the alongwind and the crosswind excitation mechanisms and response processes are discussed. Turbulence buffeting is the dominant excitation mechanism in the alongwind direction. In the crosswind direction, excitations associated with incident turbulence, vortex shedding and motion dependent excitations are the prominent mechanisms causing crosswind response. Many advanced wind codes and standards have adopted statistical and spectral analysis processes to predict wind loads and responses caused by these alongwind and crosswind excitations. The potential impact of interference excitations of tall buildings and beneficial effects of aerodynamic modifications of building shape are also reviewed in this chapter. Interference effects on the alongwind, crosswind and torsional responses of tall buildings from either an upstream or a downstream building are outlined. The beneficial effects and the economic perspectives of aerodynamic modifications of building shape in reducing the wind induced load and response of tall buildings are discussed