McKenna-Neuman, Cheryl

Plastic pollution is a growing concern, owing to its durability, ubiquity, and potential health impacts. The overall objective of this study was to assess the abundance and distribution of microplastics within Lake Scugog catchment, Ontario. This was fulfilled through two tasks (i) the development of a microplastic particle budget for the lake catchment, and (ii) the determination of the dry deposition of atmospheric microplastics in Port Perry, Ontario. The total input of microplastics into Lake Scugog (atmospheric deposition and stream inflow) was 2491 x106 mp/day, while the output (lake outflow and sedimentation) was 1761 x106 mp/day, suggesting that 29% of inputs were retained in the lake. The dry deposition of microplastics in Port Perry was 1257 mp/m2/day, which was high when compared to bulk deposition (37 mp/m2/day) in the same area. By quantifying the major pathways of microplastics better management techniques can be implemented.

Author Keywords: Catchment, Dry Deposition, Microplastics, Ontario, Particle Budget, Plastic pollution

A wind tunnel study was conducted to investigate aeolian impact ripples in sand beds of varied texture from coarsely skewed to bimodal. Experimental data is lacking for aeolian megaripples, particularly in considering the influence of wind speed on ripple morphometrics. Additionally, the modelling community requires experimental data for model validation and calibration.

Eighteen combinations of wind speed and proportion of coarse mode particles by mass were analysed for both morphometrics and optical indices of spatial segregation. Wind tunnel conditions emulated those found at aeolian megaripple field sites, specifically a unimodal wind regime and particle transport mode segregation. Remote sensing style image classification was applied to investigate the spatial segregation of the two differently coloured size populations.

Ripple morphometrics show strong dependency on wind speed. Conversely, morphometric indices are inversely correlated to the proportion of the distribution that was comprised of coarse mode particles. Spatial segregation is highly correlated to wind speed in a positive manner and negatively correlated to the proportion of the distribution that was comprised of coarse mode particles. Results reveal that the degree of spatial segregation within an impact ripple bedform can be higher than previously reported in the literature.

Author Keywords: Aeolian, Impact Ripples, Megaripple, Self-organization, Wind Tunnel

The AeolianBox is an educational and presentation tool extended in this thesis to

represent the atmospheric boundary layer (ABL) flow over a deformable surface in the

sandbox. It is a hybrid hardware cum mathematical model which helps users to visually,

interactively and spatially fathom the natural laws governing ABL airflow. The

AeolianBox uses a Kinect V1 camera and a short focal length projector to capture the

Digital Elevation Model (DEM) of the topography within the sandbox. The captured

DEM is used to generate a Computational Fluid Dynamics (CFD) model and project the

ABL flow back onto the surface topography within the sandbox.

AeolianBox is designed to be used in a classroom setting. This requires a low

time cost for the ABL flow simulation to keep the students engaged in the classroom.

Thus, the process of DEM capture and CFD modelling were investigated to lower the

time cost while maintaining key features of the ABL flow structure. A mesh-time

sensitivity analysis was also conducted to investigate the tradeoff between the number of

cells inside the mesh and time cost for both meshing process and CFD modelling. This

allows the user to make an informed decision regarding the level of detail desired in the

ABL flow structure by changing the number of cells in the mesh.

There are infinite possible surface topographies which can be created by molding

sand inside the sandbox. Therefore, in addition to keeping the time cost low while

maintaining key features of the ABL flow structure, the meshing process and CFD

modelling are required to be robust to variety of different surface topographies.

To achieve these research objectives, in this thesis, parametrization is done for meshing process and CFD modelling.

The accuracy of the CFD model for ABL flow used in the AeolianBox was

qualitatively validated with airflow profiles captured in the Trent Environmental Wind

Tunnel (TEWT) at Trent University using the Laser Doppler Anemometer (LDA). Three

simple geometries namely a hemisphere, cube and a ridge were selected since they are

well studied in academia. The CFD model was scaled to the dimensions of the grid where

the airflow was captured in TEWT. The boundary conditions were also kept the same as

the model used in the AeolianBox.

The ABL flow is simulated by using software like OpenFoam and Paraview to

build and visualize a CFD model. The AeolianBox is interactive and capable of detecting

hands using the Kinect camera which allows a user to interact and change the topography

of the sandbox in real time. The AeolianBox's software built for this thesis uses only

opensource tools and is accessible to anyone with an existing hardware model of its

predecessors.

Author Keywords: Augmented Reality, Computational Fluid Dynamics, Kinect Projector Calibration, OpenFoam, Paraview

Extremely active dust sources within selected areas of Iceland that are comprised of particles supplied from both glacio-fluvial outwash systems and volcanic eruptions (Bullard et al., 2016; Gassó et al., 2018). The supply of sediments, sparsity of vegetation, high frequency of surface winds, and lack of adequate gravel pavement to reduce sand drifting are believed to influence the duration, frequency, and magnitude of these dust events in Iceland. Apart from recent collaborative efforts to measure and model dust entrainment, emission and deposition (Prospero et al., 2012; Zwaaftink et al., 2017), several underlying physical mechanisms that are unique to cold, humid climates and the geology of Iceland are not well understood. This study specifically aims to assess and understand the physics of Icelandic dust entrainment and deposition with an emphasis on the influence of climate and the physical characteristics of the particles. A series of laboratory experiments of different configurations were carried out on several sediments collected from some of the most emissive sources in Iceland in order to understand these dust processes. The results from this study show that the increasing particle sphericity is associated with progressively smaller particle size; and an abundance of amorphous glass increases the surface area and roughness of the particles, which contributes to high porosity that alters the particle skeletal density. The particle features and climate are interlinked with the entrainment and deposition rates. For instance, coarse sediments emit higher PM concentrations than sediments containing more clay. The strong wind shear at the bed surface acts to disperse many of the tiny particle aggregates and coated liquid droplets contained within a splash structure created by the impact of a single water droplet. The deposition of suspended dust particulates is dependent on the particle characteristics and relative humidity. The retreat of glaciers and ice-cap masses in Iceland are expected to expose new dust particulate sources as the global mean temperature continues to rise (Cannone et al., 2008; Radic and Hock, 2011). Therefore, the influence of the particle characteristics and climate on the dust entrainment, emission and de- position must be accounted for in the parameterization of dust dispersion models related to suspended volcaniclastic particles.

Author Keywords: High latitude cold climate environments, Icelandic dust particle characteristics, Laser Doppler anemometer, Rain droplet impact, Settling velocity, Wind tunnel

Historically, entrances have been used for passage between two separate temperature environments, such as moving from inside to outside of a building. Energy loss through entrances is a cause for concern, as it has been known to increase energy consumption to replace the lost energy; and with the exchange of air masses and cold air entering the building, human discomfort may occur. In this research, thermal efficiency and air circulation within a Conventional Entrance (CE) and Climate Controlled Passage (CCP) are compared.

A small scale model of the CE and CCP was constructed to examine forty-eight energy exchange conditions, emulating those found through an entrance between a temperature controlled lab and the model. Instruments such as a power meter, a flow explorer laser Doppler anemometer, and thermocouples were used to measure and compare the energy consumption, velocity vectors, and temperature energy within the entrance.

Results indicate that the CCP did retain thermal energy compared to the CE. The CE developed sloped isotherm lines and air flow that enabled and maintained thermal exhaust. Conversely, the CCP developed horizontal isotherm lines and a two-layer density current to recirculate and retain thermal energy. The research demonstrates that it is possible to increase energy efficiency of entrances in many applications.

Author Keywords: Air Recirculation, Building, Entrance, Oven, Thermal Energy Efficiency, Two-layer Density Current