We study diffusion-controlled growth of a spherical droplet with a moving boundary using a physics-informed neural network (PINN) formulation. The governing diffusion equation is coupled to the interfacial mass balance, with the droplet radius treated as an additional trainable function of time. The PINN accurately reproduces the self-similar growth law and concentration profiles for a wide range of initial droplet radii, demonstrating convergence toward the asymptotic diffusive regime. The proposed approach provides a flexible and computationally efficient framework for solving moving-boundary diffusion problems and can be readily extended to include additional physical effects.
Characterization of partial wetting by CMAS droplets using multiphase many-body dissipative particle dynamics and data-driven discovery based on PINNs
The University of Western Ontario（西安大略大学）；Cold Spring Harbor Laboratory（冷泉港实验室）；Brown University（布朗大学）；University of Maryland（马里兰大学）；Clemson University（克莱姆森大学）；US Army Research Laboratory（美国陆军研究实验室）
A new type of a levitating droplet clusters composed of often transforming small aggregates of water droplets is described for the first time. Unlike earlier observed droplet clusters controlled by aerodynamic forces, which formed either an ordered hexagonal structure or a chain structure, the cluster under consideration has a hierarchical organization. Small groups of closely spaced or packed droplets with interactions controlled by the electrostatic force are combined into larger structures controlled by aerodynamic forces. Since charged droplets in the nucleus of the cluster do not have dyn…
We introduce a new experimental approach to study the structural transitions of large numbers of nanoparticle-coated droplets as their volume is reduced. We use an emulsion system where the dispersed phase is slightly soluble in the continuous phase. By adding a fixed amount of unsaturated continuous phase, the volume of the droplets can be controllably reduced, causing them to buckle or crumple, thereby becoming nonspherical. The resultant morphologies depend both on the extent of volume reduction and the average droplet size. The buckling and crumpling behavior implies that the droplet surfa…
We present a microfluidic platform for two-dimensional manipulation of water droplets immersed in bulk oil-based ferrofluid. Although non-magnetic, the droplets are exclusively controlled by magnetic fields, without any pressure-driven flow. The diphasic fluid layer is trapped in a submillimeter Hele-Shaw chamber that includes permalloy tracks on its substrate. An in-plane rotating magnetic field magnetizes the permalloy tracks, thus producing local magnetic gradients, while an orthogonal magnetic field magnetizes the bulk ferrofluid. To minimize the magnetostatic energy of the system, droplet…
We report the breakup dynamics of a magnetically active droplet (ferrofluid droplet) in a T-shaped LOC device under the modulation of a non-uniform magnetic field. We adhere to high-speed imaging modalities for the experimental quantification of the droplet splitting phenomena in the presence of a non-uniform force field gradient, while the underlying phenomena is supported by the numerical results in a qualitative manner as well. On reaching the T-junction divergence, the droplet engulfs the intersection fully and eventually deforms into the dumbbell-shaped form making its bulges to move towa…
Electrowetting on dielectric (EWOD) has emerged as a powerful tool to electrically manipulate tiny individual droplets in a controlled manner. Despite tremendous progress over the past two decades, current EWOD operating in ambient conditions has limited functionalities posing challenges for its applications, including electronic display, energy generation, and microfluidic systems. Here, we demonstrate a new paradigm of electrowetting on liquid-infused film (EWOLF) that allows for complete reversibility and tunable transient response simultaneously. We determine that these functionalities in …
We recently put in evidence (\cite{noblin2}) that combined vertical and horizontal vibrations can induced a controlled motion of a sessile supported drop. In this video we generalize this finding and demonstrate that a remote 2d controlled motion is possible. This video was submitted as part of the Gallery of Fluid Motion 2010 which is showcase of fluid dynamics videos.
Introducing controlled fluid motion inside a droplet turns out to be of outstanding scientific importance. In this work, we suggest a new method of flow manipulation inside a sessile droplet by simply deploying a static charge produced by triboelectric effect. This is physically actuated by charge transfer between the two lateral electrodes within which the droplet is entrained, triggering a strong ionized air current. The flow inside the droplet is generated due to the shear exerted at the liquid-air interface by the charged induced ionized air flow around the droplet, a paradigm that has hit…
Ultrasound-controlled stream splitting in a microfluidic coflow
Indian Institute of Technology Madras（印度马德拉斯理工学院）；Indian Institute of Technology Guwahati（印度古瓦哈提理工学院）；Indian Institute of Technology Gandhinagar（印度甘地纳加尔理工学院）
A well-known drawback of the Volume-Of-Fluid (VOF) method is that the breakup of thin liquid films or filaments is mainly caused by numerical aspects rather than by physical ones. The rupture of thin films occurs when their thickness reaches the order of the grid size and by refining the grid the breakup events are delayed. When thin filaments rupture, many droplets are generated due to the mass conserving properties of VOF. Thus, the numerical character of the breakup does not allow obtaining the desired convergence of the droplet size distribution under grid refinement. In this work, we pres…
