Transport of airborne particles within a room

Abstract

The objective of this study is to test a technique used to analyze contaminant transport in the wake of a bluff body under controlled experimental conditions for application to aerosol transport in a complex furnished room. Specifically, the hypothesis tested by our work is that the dispersion of contaminants in a room is related to the turbulence kinetic energy and length scale. This turbulence is, in turn, determined by the size and shape of furnishings within the room and by the ventilation characteristics. This approach was tested for indoor dispersion through computational fluid dynamics simulations and laboratory experiments. In each, 3 mum aerosols were released in a furnished room with varied contaminant release locations (at the inlet vent or under a desk). The realizable k approximately epsilon model was employed in the simulations, followed by a Lagrangian particle trajectory simulation used as input for an in-house FORTRAN code to compute aerosol concentration. For the experiments, concentrations were measured simultaneously at seven locations by laser photometry, and air velocity was measured using laser Doppler velocimetry. The results suggest that turbulent diffusion is a significant factor in contaminant residence time in a furnished room. This procedure was then expanded to develop a simplified correlation between contaminant residence time and the number of enclosing surfaces around a point containing the contaminant. Practical Implications The work presented here provides a methodology for relating local aerosol residence time to properties of room ventilation and furniture arrangement. This technique may be used to assess probable locations of high concentration by knowing only the particle release location, furniture configuration, inlet and outlet locations, and air speeds, which are all observable features. Applications of this method include development of 'rules of thumb' for first responders entering a room where an agent has been released and selection of sampler locations to monitor conditions in sensitive areas.

Intrusion of airborne pollen through open windows and doors

“…During the Pinus pollen season 3-35% of the outdoor concentration was simultaneously recorded in the room with two open windows and only 0.1-3.6% in that with one open window. The locations of the ventilation openings and furniture determine the floating and settling of the incoming particles (Richmond-Bryant et al 2006). Because of the position of the window the pattern of the decreasing trend in the amount of pollen is a clockwise rotation in the study room.…”

Pollen concentrations inside private cars during the Poaceae andArtemisiaspp. pollen season – a case study

“…These unexpected results could be partly explained by the fast and efficient attachment of pollen on the indoor surfaces. Depending on the design and technology of the window and air intakes/ outlet, the exterior and interior shapes and material of the car, vehicle speed, ventilation volume, turbulence and direction of the indoor air and the adhesion force of deposited pollen, different distribution figures are possible (Muilenberg et al, 1991;Richmond-Bryant et al, 2006). According to Muilenberg et al (1991), it is possible that particle momentum in relation to vehicle speed restricted the penetration of bioaerosols, such as pollen size particles, which would have tended to follow the airflow past the open side windows.…”

Modeling of occupational exposure to accidentally released manufactured nanomaterials in a production facility and calculation of internal doses by inhalation

“…These studies can be categorized based on the turbulence model used for the airflow; the k-ε or the RNG (re-normalization group) k-ε model for the airflow turbulence, [10][11][12][13][14][15] large eddy simulations, [16][17][18] and the k-μ model. 19,20 Models are categorized based on the description of the population of the particles to either Eulerian models (drift-flux), 10,[21][22][23][24][25][26] or Lagrangian particle tracking models. 11,13,[16][17][18][19]27 The common characteristic of most previous studies is the simulation of particle transport in simplified geometries of ventilated chambers.…”

“…19,20 Models are categorized based on the description of the population of the particles to either Eulerian models (drift-flux), 10,[21][22][23][24][25][26] or Lagrangian particle tracking models. 11,13,[16][17][18][19]27 The common characteristic of most previous studies is the simulation of particle transport in simplified geometries of ventilated chambers. One exception is the work of Lai and Chen, who modeled the dispersion of particles emitted during a cooking event in a realistic representation of a kitchen and adjacent living-room, as well as the works of Lin et al who modeled the transport of pathogens in aircraft cabins.…”