Active droplet manipulation on ferrofluid-infused surfaces (ongoing)
When ferrofluid is under the influence of a magnetic field, it will form beautiful spikes, i.e., liquid substructure, following the direction of magnetic filed. In this sense, ferrofluid-infused surface can be used as a viable tool to manipulate droplets.
Multi-scale morphology of three phase contact line (Ongoing)
When a liquid droplet is in contact with a solid surface, it forms a static contact line, which operates from the macroscopic to the molecular level. In this study, the contact line is divided into four different regions, each of which is located at different length scales and governed by distinct physical mechanism. In the future, we aim to develop a unified model to depict the deformation of contact line by bridging the gap between micro/nano-scale and macroscopic scale.
Contact line friction in dynamic wetting process (COMPLETED)
The stress singularity, which is triggered by the relative motion of three phase contact line to solid surfaces, has remain a long-lasting debate. The concept of contact line friction was proposed to account for the energy dissipation and accommodate the interfacial slip during the dynamic wetting process. In this study, we established a model to interpret the origin of contact line friction for droplets on flat and superhydrophobic nano-structured surfaces under the framework of molecular kinetic theory. We also demonstrated the lotus-leaf effect by showing how the surface structure reduces the frictional force between Cassie-state droplets and solid surfaces.
Coalescence INDUCED JUMPING OF NANODROPLETS (ONGOING)
When two or more droplets meet each other on a superhydrophobic surface, the breaking of symmetry for droplets induces a higher pressure at the droplet base and drives the drop to jump away. During this process, the efficiency of energy conversion, i.e., from the excess surface energy to translational kinetic energy, is as low as 6% and the energy dissipation mechanism obscure. In this study, we will use molecular dynamics simulations as a tool to study the size effects and energy dissipation in the process of coalescence induced jumping of nanodroplets.
Modeling and optimization of tubular microbial fuel cells (Completed)
Microbial fuel cells (MFCs) are considered as a promising technology for sustainable wastewater treatment with energy recovery. The anode of an MFC plays a key role in conversion of organic compounds to electricity, and thus understanding the multiphysics within the anodic compartment will be helpful with MFC optimization and scaling-up. In this study, a multi-order Butler-Volmer reaction model was proposed for the first time to compute organic consumption and energy recovery. Computational fluid dynamics (CFD) was applied to analyze the hydrodynamics and species transport inside the anodic compartment. The results of this study have demonstrated the viability of coupling CFD with a multi-order reaction model to understand the key operating factors of an MFC.