Large Eddy Simulation of Wind Flow over A Realistic Urban Area

Gokhan Kirkil,Ching-Long Lin

doi:10.3390/computation8020047

Abstract

A high-resolution large eddy simulation (LES) of wind flow over the Oklahoma City downtown area was performed to explain the effect of the building height on wind flow over the city. Wind flow over cities is vital for pedestrian and traffic comfort as well as urban heat effects. The average southerly wind speed of eight meters per second was used in the inflow section. It was found that heights and distribution of the buildings have the greatest impact on the wind flow patterns. The complexity of the flow field mainly depended on the location of buildings relative to each other and their heights. A strong up and downflows in the wake of tall buildings as well as large-scale coherent eddies between the low-rise buildings were observed. It was found out that high-rise buildings had the highest impact on the urban wind patterns. Other characteristics of urban canopy flows, such as wind shadows and channeling effects, are also successfully captured by the LES. The LES solver was shown to be a powerful tool for understanding urban canopy flows; therefore, it can be used in similar studies (e.g., other cities, dispersion studies, etc.) in the future.

Highlights

Wind flow over single buildings, a group of buildings or cities, is named as urban canopy flow
The distribution of the buildings has the greatest impact on wind flow patterns
It was found that the distribution of buildings and their height have the greatest effects on flow patterns

Summary

Introduction

Wind flow over single buildings, a group of buildings or cities, is named as urban canopy flow. Five different CFD models (Four RANS and one LES) were used to model wind flow around a group of buildings in the New York City metropolitan area [9]. RANS simulations of wind flow around CBD of Oklahoma City using FLUENT were performed by [12]. Several RANS simulations of the flow around buildings were performed by [14] in the CBD of Oklahoma City. Their model, RUSTIC, agreed well with the wind velocity and TKE measurements, especially downwind of the city and downwind of the tallest building. An LES model with wall functions is used to investigate complex flow patterns in the CBD of Oklahoma City. What is the effect of high-rise buildings inside a business district on urban wind flow? How are along-the-canyon wind flows formed? What are the flow structures in a street canyon formed by similar height low-rise buildings?

Description of the Numerical Model and Computational Setup

Results

Conclusions andand