Improvement of a Diagnostic Urban Wind Model for Flow Fields around a Single Rectangular Obstacle in Micrometeorology Simulation

Abstract

In general, computational fluid dynamics (CFD) models incur high computational costs when dealing with realistic and complicated flows. In contrast, the mass-consistent flow (MASCON) field model provides a three-dimensional flow field at reasonable computational cost. Unfortunately, some weaknesses in simulating the flow of the wake zone exist because the momentum equations are not considered in the MASCON field model. In the present study, a new set of improved algebraic models to provide initial flow fields for the MASCON field model are proposed to overcome these weaknesses by considering the effect of momentum diffusion in the wake zone. Specifically, these models for the wake region are developed on the basis of the wake models used in well-recognized Gaussian plume models, ADMS-build and PRIME. The MASCON fields provided by the new set of wake zone models are evaluated against wind-tunnel experimental data on flow around a wall-mounted rectangular obstacle. Each MASCON field is compared with the experimental results, focusing on the positions of the vortex core and saddle points of the vortex formed in the near-wake zone and the vertical velocity distribution in the far-wake zone. The set of wake zone models developed in the present study better reproduce the experimental results in both the wake zones compared to the previously proposed models. In particular, the complicated recirculation flow which is formed by the union of the sidewall recirculation zone and the near-wake zone is reproduced by the present wake zone model using the PRIME model that includes the parameterization of the sidewall recirculation zones.

Simulating Microscale Urban Airflow and Pollutant Distributions Based on Computational Fluid Dynamics Model: A Review

“…In the vicinity of a single building, the flow field (Figure 2) is characterized by distinct regions, including the upstream recirculation, rooftop recirculation zone, near-wake zone, and far-wake zone [36]. When multiple buildings encircle an individual structure, the flow fields intersect and interact, giving rise to intricate flow patterns both among the buildings and within the building array.…”

Aerodynamic Characteristics of Different Heights Buildings in Close Proximity

“…Replenishment of the ejected air takes place due to the surface layers, which are inhibited, can change direction, carry out a vortex movement and flow from the area of increased pressure to the under-pressure zone. On the windward side there is a stagnation zone (aerodynamic wake zone) [26]. The length of this zone is taken from the condition that the speed of the flow in it is at least 95% of the speed of the undisturbed flow at the same height from the surface of the earth.…”