I am currently a postdoctoral scholar at the University of Washington. I have years of research experience utilizing computational imaging to study fluid mechanics. In particular, I use holographic, tomographic imaging, and machine learning tools to analyze turbulent, interfacial, and biological flows. Examples include jet and spray, complex droplets, cavitation, and cerebral aneurysm flows.
Fragmentation of an immiscible jet can be found in many industrial, environmental, and biological applications. However, quantitive data are hard to obtain experimentally in optically opaque flow, especially in the nearfield where dense oil ligaments and droplets exist. Liquid-liquid refractive index matching and simultaneous Particle Image Velocimetry (PIV) and Laser Induced-Fluorescence (PLIF) are developed to measure interface distributions and turbulent statistics. The result shows the presence of the second phase significantly increases the turbulence level than the single-phase jet. Moreover, the turbulence production in the dispersed phase is drastically different than the continuous phase.
Compound droplets containing multiple water droplets, some with smaller oil droplets, regularly form at jet Reynolds numbers Re>1358. The origin of some of the encapsulated water droplets can be traced back to the entrained water ligaments during the initial roll-up of Kelvin–Helmholtz vortices. Machine learning technique was applied to distinguish compound droplets and regular droplets. On average, the interior pockets raise the oil-water interfacial area by 15 %, increasing with the diameter and axial location. Also, while the oil droplets are deformed by the jet’s shear field, the interior interfaces remain nearly spherical, indicating a quiescent micro-environment in the local high shear zone.
Accurate experimental measurement of droplet size distribution is crucial to predict the dispersion of pollutants in the event of an oil spill. Submersible Miniaturized Inline Holographic Camera (MiniHolocam) was built from scratch and deployed to in situ quantify droplet size distribution of a crude oil jet in crossflow. The instrument can also be applied to study aerosol generation and oil-water interfaces.
Three-dimensional locations and size distributions of droplets or particles can be obtained by hologram reconstruction, modified Hough transform and parameter space selections.
This study investigates the effects of premixing oil with chemical dispersant at varying concentrations on the flow structure and droplet dynamics within a crude oil jet transitioning into a plume in a crossflow. It is motivated by the need to determine the fate of subsurface oil after a blowout disaster. The flow within the plume consists primarily of a pair of counterrotating quasi-streamwise vortices (CVP) that characterize jets in crossflows. The size of droplets trapped by the CVP is predicted correctly using a trapping function based on a balance of forces on a droplet located within a horizontal eddy. This study is in collaboration with Prof. David Murphy and Dr. Kaushik Sampath.
Cavitation in the flapper–nozzle pilot stage is an important source for the noise, performance deterioration, and even failure of electrohydraulic servo-valves. In this study, experimental and numerical investigations of the cavitation phenomenon appearing in the flow field between the flapper and nozzle of an electrohydraulic servo-valve are carried out. As a result, cavitation source locations are confirmed as the nozzle tip and flapper leading edge. This study is supervised by Prof. Songjing Li, and in collaboration with Dr. Nay ZarAung, Dr. Shengzhuo Zhang, and Dr. Junzhang Cao.
Besides research, I also serve the community by solo and chamber music performing, teaching, and score arrangement.
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