Parçacık görüntülemeli hız ölçümü (PIV) ve farklı görüntüleme yöntemlerinin birleştirilerek biyolojik akışların incelenmesi

Biological flows are important components of biological systems including cardiovascular, respiration or neural systems of species. Biological flows affect different systems by interacting with endothelial cells in vessels or receptor neurons in olfactory organ. In this thesis, four different biological flows are investigated. First one is hemodynamics in right vitelline artery (RVA) of chicken embryo. Second research is the investigation of suction and pumping flows at mussels. Third research is to explore suction feeding in zebrafish embryo. Last research is to investigate the effect of fluid dynamics on the olfaction of zebrafish embryo. In first research, we investigated the role of hemodynamics forces on the developing cardiovascular system of chicken embryo. Furthermore, clinical experience suggests that perturbed flow disrupts the normal vascular growth process as one etiology for congenital heart diseases (CHD) and for fetal adaptation to CHD. However, the relationships between hemodynamics, gene expression and embryonic vascular growth are poorly defined due to the lack of concurrent, sequential in vivo data. In this study, a long-term, time-lapse optical coherence tomography (OCT) imaging campaign was conducted to acquire simultaneous blood velocity, pulsatile micro-pressure and morphometric data for 3 consecutive early embryonic stages in the chick embryo. In conjunction with the in vivo growth and hemodynamics data, in vitro reverse transcription polymerase chain reaction (RT-PCR) analysis was performed to track changes in transcript expression relevant to histogenesis and remodeling of the embryonic arterial wall. Our non-invasive extended OCT imaging technique for the microstructural data showed continuous vessel growth. OCT data coupled with the PIV technique revealed significant but intermitted increases in wall shear stress (WSS) between first and second assigned stages and a noticeable decrease afterwards. For the suction and pumping performance of mussels, Hydrodynamic performance of marine mussel, Mytilus galloprovincialis, is studied with time-resolved particle image velocimetry. We evaluated inhalant flow, exhalant jet flow, suction performance, and flow control capabilities of the mussels quantitatively. Inhalant flow structures of mussels are measured at the coronal plane first time in literature. Nutrient fluid is convected into the mussel by three-dimensional sink flow. Inhalant velocity reaches its highest magnitude inside of the mussel mantle while accelerating outward the mussel. We calculated pressure gradient at the coronal plane. As inhalant flow approaches mussel shell tip, suction force generated by the inhalant flow increases and becomes significant at shell tip. Likewise, exhalant jet flow regimes are studied for 17 mussels. Mussels can control their exhalant jet flow structure from single potential core region to double one or vice versa. Peak exhalant jet velocity generated by the mussels changes between 2.77 cm/s and 11.1 cm/s as a function of mussel cavity volume. Measurements of hydrodynamic dissipation, at the sagittal plane, revealed no interaction between the inhalant and exhalant jet flow, indicating energy efficient synchronized pumping mechanism. This efficient pumping mechanism is associated with the flow-turning angle between inhalant and exhalant jet flows, ~90o (s.d. 12o). In the third research, the hydrodynamics of suction feeding is investigated. Suction feeding is critical for the survival of fish larvae; failure to capture food during the onset of autonomous feeding can rapidly lead to starvation and mortality. Fluid mechanics experiments that investigate the suction feeding of suspended particles are limited to adult fishes, which operate at large Reynolds numbers. This manuscript presents the first literature results in which the external velocity fields generated during suction feeding of early zebra fish larvae (2500 to 20000 μm total length) are reported using time-resolved microscopic particle image velocimetry (μPIV). For the larval stages studied, the maximum peak suction velocity of the inflow bolus is measured at a finite distance from the mouth tip and ranges from 1 to 8 mm/s. The average pressure gradient and the velocity profile proximal to the buccal (mouth) cavity are calculated and two distinct trends are identified. External recirculation regions and reverse flow feeding cycles are also observed and quantified. One of the unresolved questions in fish suction feeding is the shape and dynamics of the buccal (mouth) cavity during suction feeding; optical coherence tomography (OCT) imaging is found to be useful for reconstructing the mouth kinematics. The projected area of the mouth cavity during the feeding cycle varies up to 160% and 22% for the transverse and midsagittal planes, respectively. These findings can inspire novel hydrodynamicaly efficient biomedical and microfluidic devices. Olfaction system of zebrafish embryo is also subject of fluid dynamics. Neural cells and motile cilia on top of it cover olfactory organ of the embryos. Motile cilia generate flow around the nose of zebrafish embryo. In our research, we showed that spatially organized motile cilia beat asymmetrically and generated three-dimensional flow around nose. We also showed that the flow generated by motile cilia attracts odor to nose at stagnant environments. Our results showed that the flow improves the sensitivity and temporal resolution of olfactory computation.