Session: 11-19-01: Fluid Measurements and Instrumentation/Young Engineer Paper (YEP) Contest

Paper Number: 166586

Turbulent Flow and Mixing Within and Around Building Environments 

Understanding the flow characteristics of airborne contaminants in urban environments is increasingly critical to a wide variety of applications, including urban planning, public health, and architectural design. With ever increasing global urbanization, understanding how pollutants or hazardous chemicals interact with dense urban landscapes is crucial for maintaining public wellbeing. While much is understood regarding internal building mixing and external flow around structures, much less is known about the interactions between internal and external mixing. This work examines airflow and contaminant interactions between two ventilated buildings, including the impact of varying wind angles and building spacing in the streamwise direction. Complementary laser-based imaging and magnetic resonance imaging (MRI) techniques are applied to enhance understanding of multi-building wake interactions. A small-scale geometric model consisting of two buildings within a turbulent flow channel with a fully-turbulent Reynolds number of ~6,000 is examined to this end. These buildings are ventilated by apertures on the windward and leeward sides and arrayed such that flow from the upstream building impacts the downstream one. Rotating the building array relative to the dominant flow direction (at intervals of 0°, 22.5°, and 45°) as well as varying building spacing (0.5 building width, 1 building width, 1.5 building width) enables data collection for the most relevant cases of urban interaction. Experimental use of magnetic resonance velocimetry (MRV) allows measurement of three-dimensional, time-averaged flow velocity fields. This technique does not require optical access, allowing insight to building-internal quantities in addition to external flow. Laser-based diagnostics of planar laser induced fluorescence (PLIF) and particle image velocimetry (PIV) complement this measurement technique by providing instantaneous data for local contaminant concentrations and flow velocities, respectively. During PLIF testing, the release of an upstream scalar contaminant within the flow channel, in the form of a fluorescent dye, provides insight into the impact of ventilation features and building interactions on plume dispersion. PIV uses reflective tracker particles injected into the flow channel to determine instantaneous velocity throughout the flow. Results of interest include global transport effects, building-internal concentrations, and local plume residence times. Understanding the wake interactions between structures is critical to model the dispersion of airborne contaminants and pollutants within an urban environment, with applications to pollutant modeling, urban design, and emergency response. This work expands on current research which relies predominantly on field tests. The novel experimental methodology may be applied to scenarios otherwise unfeasible for field test validation due to requirements for extensive detailed data collection or boundary condition control. Ultimately, these results can be used to validate quick-running emergency response models. Overall, this work developed an experimental methodology to enhance understanding of multi-building interactions and complement scenarios where field tests prove unfeasible due to requirements for detailed measurement and boundary condition control. 

Presenting Author: Haley Kampert United States Military Academy

Presenting Author Biography: Haley Kampert is a U.S. Army engineer officer and recent graduate from the United States Military Academy with a B.S. in mechanical engineering. She is currently working towards her M.S. in biomedical engineering at Boston University, and is originally from Ellicott City, Maryland.

Authors:

Haley Kampert United States Military Academy
Tavis Cahanding United States Military Academy
Pierson Ederle United States Military Academy
Tuhin Bandopadhyay University of Illinois Urbana-Champaign
Pranet Patil University of Illinois Urbana-Champaign
Joseph Pelletiere University of Illinois Urbana-Champaign
Marc Samland United States Military Academy
Laura Villafane University of Illinois Urbana-Champaign
Andrew Banko United States Military Academy
Bret Van Poppel United States Military Academy