Department of Mechanical and Materials Engineering Graduate Theses

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    Design and Validation of an Accessible and 3D-Printable 24-Channel Peristaltic Pump for Cell Culture Research
    (2024-09-05) Huitema, Erin; Mechanical and Materials Engineering; Ploeg, Heidi-Lynn
    Peristaltic pumps are an essential part of biomedical research worldwide. The peristaltic pumps used for cell culture are precise and accurate machines which cycle media to and from cells during experiments. Commercial peristaltic pumps pose barriers for all labs due to expensive purchase and repair costs, however they are especially inaccessible for labs with limited research funding and excessive importation time. 3D printing has been shown to be an accessible method of fabrication worldwide [1]. In 2020, a 3D-printable peristaltic pump was developed to address these concerns, called the FAST-pump [2]. This pump design has 8 channels, allowing for labs to fabricate their own pumps and conduct research with sample sizes of 8 or less. However, large experimental sample sizes are advantageous by increasing the statistical power and the number of independent variables per experiment and are often utilized in cell culture research applications [3], [4], [5]. This thesis aimed to create and validate an accessible 24-channel peristaltic pump design for research labs that is low-cost, locally resourced, user-friendly, reliable, and allows for triple the experimental number of samples than existing 3D-printable peristaltic pumps. The product was designed according to the needs of stakeholders: researchers at the Center for Health Innovation (CHI) at Queen’s University and the B3MAT research group at Universidad Adolfo Ibanez in Viña del Mar, Chile. A House of Quality (HoQ) was constructed to determine customer requirements and the associated functional requirements of the design. A 3D-printable, 24-channel peristaltic pump was designed, fabricated with ABS-M30 material, and assembled with off-the-shelf components. The assembled pump was iterated and validated to compare its performance to a commercial 24-channel peristaltic pump. This thesis demonstrated the reduced cost (6.1%) of a 24-channel 3D-printed peristaltic pump and compared its performance to the commercial alternative. This thesis also provided insights and recommendations for next steps of the pump design and validation, and provided open-source resources available in English: STL and CAD files, an Arduino IDE script, and comprehensive user guide manual for the assembly, operation, and calibration of the 3D-printable 24-channel peristaltic pump.
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    Wall-Modelled Large-Eddy Simulations of Non-Equilibrium Turbulent-Boundary Layer with Roughness
    (2024-08-30) Salomone, Teresa; Mechanical and Materials Engineering; Piomelli, Ugo; De Stefano, Giuliano
    This study focused on numerical simulations of flow over rough walls using wall models for Large-Eddy Simulation (LES). Wall-modeled simulations are necessary due to the high computational cost of resolving flows at high Reynolds numbers, particularly with roughness. While wall models have been effective in turbulent flow simulations, their true predictive capability must be assessed in scenarios with non-equilibrium effects. The aim here is to evaluate various wall models’ performance in LES for predicting flows influenced by changes in surface roughness or pressure gradients. Wall-modelled Large-Eddy Simulations (WMLESs) have been performed with the log-law based Equilibrium Wall Model (EQWM), and the Generalized Moody Diagram (GMD) model [Meneveau, J. Turbul. 21(11):650–673 , 2020]. Furthermore, Improved Delayed Detached-Eddy Simulation (IDDES) [Shur et al., Int. J. Heat Fluid Flow, Vol. 29, pp. 1638-1649, 2008] and Integral Wall-modelled Large-Eddy Simulations (iWMLESs) were conducted. The Drag Model (DM) of Varghese and Durbin [J. Fluid Mech., Vol. 897, pp. A10, 2020] is also used in conjunction with both the EQWM and IDDES. The Lagrangian Relaxation Towards Equilibrium (LaRTE) [Fowler et al., J. Fluid Mech. 934:A44, 2022] model, was considered as representative of iWMLES, which distinguishes between quasi-equilibrium wall stress evolution and non-equilibrium effects. A novel formulation of LaRTE for rough walls was introduced to facilitate a seamless transition between behaviors characteristic of smooth and rough flow conditions. Results showed the memory feature of the log-law based EQWM in its smooth adaptation to the new surface condition, while IDDES exhibited non-physical adjustments in the mean velocity profile after surface transitions. The newly extended LaRTE model for rough surfaces proved essential for capturing flow field discontinuities induced by surface heterogeneity, outperforming other conventional wall models. The performance of wall models appears to be quite satisfactory across a range of pressure gradient applications, covering scenarios from mild to strong pressure gradients, including transitions between favorable pressure gradient (FPG) to adverse pressure gradient (APG) and vice versa. However, challenges persist in accurately capturing the flow evolution in the APG region, and further study is needed to explore the applicability of smooth-walls flow assumptions for roughness modelling.
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    Evaluating Lower Limb Alignment in Knee Osteoarthritis Patients Using Markerless Motion Capture
    (2024-08-21) Calderone, Jacob; Mechanical and Materials Engineering; Deluzio, Kevin
    Knee osteoarthritis (OA) is one of the most prevalent musculoskeletal diseases in the world, where patients diagnosed with this disease report pain, limited mobility, and an overall compromised functional status. Marked abnormality in lower limb alignment is often associated with the progression of knee OA. Varus or valgus malalignment is assessed clinically from a static radiograph. Incorporating a dynamic assessment into the clinical workflow would provide clinicians an opportunity to examine the knee joint under natural loading conditions. Markerless motion capture using Theia3D is a potential technique to examine lower limb alignment that can be used to augment current healthcare practices. Contrary to other motion capture technology, markerless motion capture does not require palpating patients with infra-red markers or require a specialized laboratory for data collection. The first study in this dissertation evaluated the ability of markerless motion capture to quantify frontal plane lower limb alignment in an orthopedic population. The knee adduction angle was computed to assess both static and dynamic lower limb alignment and to determine if the measurable outcomes were correlated. Ninety-two patients completed a double limb support stand task (static) and a gait task (dynamic) during the same visit. Statistically significant differences were found between predominantly advanced medial and lateral knee OA groups from static and dynamic alignment. The static and dynamic alignment measures were also highly correlated, consistent with previous work. The second study in this dissertation investigated the level of agreement between markerless motion capture and long leg radiology to measure static frontal plane alignment. A mobile camera system was created to collect markerless data in the radiology room. Twelve patients underwent a long leg radiograph immediately followed by markerless motion capture data collection. The static hip-knee-ankle angle measurements were found to be highly correlated between systems. However, notable measurement variance existed between systems prompting additional exploration into inter-joint distances, segment lengths, influence of patient BMI, and camera configuration. Overall, markerless motion capture using Theia3D shows promise to act as a supplementary technique for healthcare practitioners to deploy in their clinical assessment of those diagnosed with musculoskeletal diseases such as knee OA.
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    Knee Joint Loading and Fracture Risk Analyses of Patients with Benign Bone Tumours: A Finite Element Analysis
    (2024-08-21) Cameron, Emily; Mechanical and Materials Engineering; Ploeg, Heidi
    Primary benign bone tumours are uncommon and most often affect children and young adults. Chondroblastoma, giant cell tumours, and aneurysmal bone cysts, are benign, aggressive tumours that commonly arise in the epiphysis of long bones, such as the proximal tibia or distal femur. Curettage and bone grafting are common treatment methods for benign bone tumours. Recent literature illustrates that clinical practices for determining pathologic fracture risk during joint loading are inaccurate, and often lead to unnecessary surgical procedures or revision surgeries. This thesis aimed to assess the predictive capability of patient specific computed tomography based finite element analysis (CTFEA) compared to traditional orthopaedic clinical fracture risk assessment methods, explore its potential impact on pre-operative surgical decision making and treatment planning, and evaluate its ability to predict safe levels of joint loading for patients with a diagnosis of benign bone tumors. The pre-operative computed tomography (CT) scans from four female patients in the Kingston Health Sciences Centre (ethics protocol: HSERB, TRAQ# 6039359) were included in the current research study. A well-established and experimentally validated workflow for developing patient specific finite element models of bone from CT scans was used to create diseased and intact tibiofemoral joint models for each patient within the dataset. A tibiofemoral joint loading sensitivity analysis was conducted to evaluate motion capture and ground reaction force data collected as part of this thesis and published instrumented total knee replacement data with respect to patients included within this study. Patient specific fracture risk and factor of safety (FOS) analyses were conducted for the diseased and intact bone (distal femur or proximal tibia) of each patient within this study during normal walking gait. Cases without high risk of fracture during walking had fracture and FOS analyses performed for jogging. Cases with high risk of fracture during walking had fracture and FOS analyses performed for partial weight bearing using a mobility device. This thesis provides insights into the development of patient-specific CTFEA, methods for evaluating tibiofemoral joint loading, patient-specific fracture risk assessment, and determining safe levels of locomotive activity in patients with primary benign bone tumors near the knee joint.
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    Advancing Industrial Smokeless Flaring: Experimental and Computational Studies into Swirl Air-Assist Burners
    (2024-07-11) Hou, Jianfeng; Mechanical and Materials Engineering; Birk, A. Michael
    The flame thermal radiation characteristics of two prototype swirl air-assist burner designs, associated with industrial smokeless flaring, were experimentally and computationally studied. The work was driven by two main interests: first, to explore the potential of swirling air-assist flare tips in reducing thermal radiation levels, decreasing soot emission, and stabilizing flames in cross-wind; second, to develop an affordable Reynolds Averaged Navier-Stokes (RANS) based computational fluid dynamics (CFD) methodology validated with these specific flames to facilitate further burner designs. The experimental investigation involved two burner configurations. The first burner, named the accelerating swirl burner, was evaluated using two-phase propane at rates of 3 kg/min and 6 kg/min. Compared to an open flare and the burner setting without assist air, the burner with a moderate active assist air supply effectively reduced the visible flame area and emissive power, while also enhanced flame stability in cross-wind. The second burner, called the diffusing swirl burner, equipped with two powerful centrifugal fans, was tested under assist-air to fuel ratio (AAFR) ranged from low, moderate, high to maximum. An increase in AAFR introduced recirculation regions near the burner outlet, led to reductions in visible flame area, emissive power, and radiative heat flux. CFD simulations of both swirl burners in ANSYS Fluent captured the general trends observed in experiments, such as decrease in flame size and emissive power. For the diffusing swirl burner, however, the flame shape responsiveness to AAFR changes in CFD lagged behind that in experimental observations, with flame area discrepancies ranging from 11%-42% compared to the flame contours observed at 800 K. Predictions of emissive power deviated from the experimental values by 3%-67%. Regarding soot production, the model predicted a maximum 84% reduction in soot volume fraction, closely aligning with the observed transition from slightly sooty to smokeless flames in experiments.