Computational fluid dynamics (CFD) study investigating the effects of torso geometry simplification on aspiration efficiency

Anderson, Kimberly Rose. "Computational fluid dynamics (CFD) study investigating the effects of torso geometry simplification on aspiration efficiency. ii ACKNOWLEDGMENTS First and foremost I would like to thank my advisor, Renée. I cannot possibly thank you enough for providing me with the support and direction to complete this work. You sparked my interest in research and set me on the path to pursuing my PhD, and I will always be grateful to you for that. Thank you for indulging me on my various interests and side projects and providing me with the knowledge and resources to pursue those. And thank you for your guidance and focusing me on the tasks at hands when my ambitions got the better of me. I will always be honored to call you my advisor and mentor. I want to thank my family for always being there and supporting me through everything. To my parents, I can't express my gratitude enough. I wouldn't be where I am today if it wasn't for you instilling in me a love of learning and pushing me to always do my best. I appreciate your unfaltering belief in my ability to succeed and your unconditional support. And lastly, to my friends who were there to support me, who shared in the laughter and celebrations, and offered encouragement and support through the tears. Thanks for being there and helping me through this. iii ABSTRACT In previous studies truncated models were found to underestimate the air's upward velocity when compared to wind tunnel velocity studies, which may affect particle aspiration estimates. This work compared aspiration efficiencies using three torso geometries: 1) a simplified truncated cylinder; 2) a non-truncated cylinder; and 3) an anthropometrically realistic humanoid body. The primary aim of this work was to (1) quantify the errors introduced by using a simplified geometry and (2) determine the required level of detail to adequately represent a human form in CFD studies of aspiration efficiency. Fluid simulations used the standard k-epsilon turbulence models, with freestream velocities at 0.2 and 0.4 m s-1 and breathing velocities at 1.81 and 12.11 m s-1 to represent at-rest and heavy breathing rates, respectively. Laminar particle trajectory simulations were used to determine the upstream area where particles would be inhaled. These areas were used to compute aspiration efficiencies for facing the wind. Significant differences were found in vertical velocity and location of the critical area between the …