Research
Drag Reduction and Flow Control by Super-Hydrophobic Coatings
The hydrodynamic skin-friction in turbulent flows contributes to 60-70% of the total drag of most surface and subsurface vessels. Reducing the friction drag could lead to improvement of speed, range and maneuverability, as well as a reduction of fuel consumption and CO2 emission. Recently, superhydrophobic surface (SHS), inspired from the lotus leaf, has been shown to achieve a substantial drag reduction, as high as 90%. The SHS traps a thin gas layer between the solid surface and flowing liquid, and thereby an effective slip boundary. However, implementing SHS in real large-scale engineering systems, such as ships, is still highly challenging for issues, such as non-uniform surface roughness, unstable gas layer, and gas dissolution. Our lab aims to address these issues by performing research at the following areas:
– Diffusive and convective gas transfer from SHS to surrounding liquid.
– Stability of gas layer on SHS in turbulent flows.
– Flow structure and Turbulence on large SHS in fully developed flows.
Bubble Formation on Complex Surfaces
Bubble formation is a fundamental topic in multiphase flows and has broad industrial and biomedical applications, including cooling of high-power device, froth floatation, surface cleaning, drug delivery, etc. Predicting and controlling the bubble size are highly demanded in these applications since the bubble size determines the heat and mass transport. Our lab perform experimental studies to understand bubble formation on complex micro/nano-texture surface.
Bacteria-Surface Interactions
Most bacteria in the biosphere live in communities that are associated with surfaces. Adhering to surfaces provides bacteria with many advantages, including nutrient capture, protection from predation, and facilitating the conservation of the genotype. However, bacterial adhesion to surfaces is problematic in a wide range of areas, including implanted medical devices, water purification systems, food processes, and marine industries. In our lab, we are working on the following areas:
– Understanding bacterial-surface interaction by 3D particle tracking.
– Anti-bacterial techniques based on super-hydrophobic surfaces.
Collective Behavior
Collective behavior is cornerstone of many biological systems, from the cell colonies, insect swarms, bird flocks, to human crowds. Living in groups can provide numerous benefits, including predator avoidance, resource exploitation, and energy savings. We use a combination of experimental observations and mathematical modelings to uncover the mechanism of collective behavior. By learning the natural systems, we aim to design efficient multi-robotic systems. [Read More]
Optical Technologies and Particle Tracking
Our knowledge of complex flow phenomena is often limited due to a lack of experimental tools. In our lab, we are developing new optical measurement techniques for various applications, including turbulent flows, blood cell morphologies, cavitation phenomena, bubble dynamics, micro-swimmers in ocean, and bacterial motions. We are specialized in the following two methods:
– 3D particle tracking by Digital Holographic Microscopy.
– Stereo-tracking by multi-view, multi-camera imaging.
