Particle-laden flows, characterized by the motion of discrete solid particles or droplets within a continuous carrier medium, are ubiquitous in various fields, spanning from environmental phenomena to industrial processes. Understanding these complex flows, particularly within intricate biological systems such as the human aorta, presents significant challenges and opportunities in fundamental and applied research. This study investigates the passive control of the fate of embolic particles in the aorta grafted with the cannula of a left ventricular assist device (LVAD). An LVAD is a mechanical heart-assist pump that is used for severe heart failure patients awaiting heart transplants or as a permanent therapy. A risk factor with this type of device is the transport of blood clots (formed in the left ventricle or within the pump) to the brain vasculature bed, leading to an ischemic stroke event. Previous studies have highlighted the influence of the cannula-aorta graft angle on hemodynamics and particle trajectories. However, there have been inconsistencies across numerical simulations, as well as a sore lack of experimental validations. This has served as the motivation for this dissertation to design and develop a robust experimental-based framework to study the transport of inertial particles in a biofluidic setting. The framework has been complemented by high-fidelity computational studies. For the geometry, four patient-specific cases as well as two idealized aortic computer-aided design (CAD) models have been developed and used for experimental and numerical analyses. The idealized model development process integrates statistical data from the literature alongside morphological parameters extracted from the recruited patients' models. A set of experimental studies is conducted to investigate the dynamics and trajectories of particles within the developed aortic models. Water has been used as the working fluid at two target flow rates o (open full item for complete abstract)

Concentrated suspensions have been an area of research for years, with wide range of applications in industry and nature. One of the main issues encountered when handling such materials is the development of particle concentration inhomogeneities under shear, as a result of sedimentation and Shear Induced Migration (SIM). Experimental techniques to study the dynamics of suspension flows thus require high spatial and temporal resolutions to capture profiles of solid volume fraction in both transient and steady-state conditions. When optical access is possible, methods like particle tracking are employed due to their high temporal and spatial resolutions; however, optical access is limited in real systems and even in the majority of model suspensions. In these last cases, methods involving Nuclear Magnetic Resonance (NMR) are employed. These methods require the use of homemade devices, which makes them rare and expensive. Moreover, the time required for data acquisition is large, making them incapable of studying fast changes and monitoring volume fraction evolutions continuously. Available methods may thus not fully meet all the requirements to study most suspension flows. The objective of this thesis is to study SIM of particles in yield stress fluids. The contribution of this thesis comes into two parts. First, we introduce a new technique based on X-ray radiography with high temporal (O(0.1 sec)) and spatial (O(10 μm)) resolutions to overcome the above-mentioned limitations. This technique allows us to study the evolution of the solid volume fraction in fast suspension flows regardless of optical access. We benefit from the axial symmetry in our flow configuration, a wide gap Couette setup, to extract a 3D solid volume fraction field from a single X-ray projection image. We propose a mathematical algorithm based on the inversion of Abel transform in conjunction with H1 regularization and data denoising to measure the solid volume fraction field in suspensions i (open full item for complete abstract)