The leading challenges in science and technology of this century are clearly the quantitative understanding of biosystems. The research focus is multi-scale and multi-physics modeling of biosystems based on immersed boundary/continuum methods. Human blood is a biological fluid composed of deformable cells, proteins, platelets, and plasma. Human circulatory systems have evolved to supply nutrients and oxygen to and carry the waste from the cells of multicellular organisms through the transport of blood. In the study of the heart, arteries, veins, microcirculation, and pulmonary blood flow, multi-scale and multi-physics coupling of fluids and solids plays an important role. In simulation models, many blood constituents should be represented as immersed flexible shells/beams and solids with various material properties. Furthermore, such models can also be extended to various cardiovascular implants. The closing dynamics of the mechanical valves creates pressure transients that excessively load cells, valve structures, and surrounding tissues, and form cavitation bubbles, which on collapse can cause hemolysis and thrombus initiation. In reality, large motions of flexible structures immersed in biological fluids not only contribute to complex macroscopic stagnation and regurgitation flow behaviors but also affect microscopic chemical/physical changes due to their interaction with proteins, cells, and particles. In fact, the major problems of existing cardiovascular implants can be traced back to the lack of effective modeling tools. These tools are essential for the fine tuning of the designs according to individual organ sizes and physiological flow conditions as well as better understanding of fatigue lifespan of biocompatible materials and atherosclerosis/thrombotic processes. Currently, the intricate structural behaviors, in particular those of immersed flexible shells/beams and solids, are still not well understood. This is due to the enormous difficulties in combining complex nonlinear structural motions with equally complex fluid motions. The goal of my research work is to overcome these difficulties by developing new immersed boundary/continuum methods which will provide a platform for effective modeling of highly deformable shells/beams and solids immersed in biological fluids and facilitate further research in multi-scale and multi-physics coupling of complex fluid-solid systems with microscopic models.
Soft Objects Impact, Conform, and Pass Over an Elastic Vessel Bifurcation
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