Author
Kensuke Yokoi
Other affiliations: Hokkaido University, University of California, Los Angeles, Ibaraki University ...read more
Bio: Kensuke Yokoi is an academic researcher from Cardiff University. The author has contributed to research in topics: Level set method & Numerical analysis. The author has an hindex of 13, co-authored 31 publications receiving 852 citations. Previous affiliations of Kensuke Yokoi include Hokkaido University & University of California, Los Angeles.
Papers
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TL;DR: In this article, the authors numerically investigated liquid droplet impact behavior onto a dry and flat surface using a coupled level set and volume-of-fluid framework, volume/surface integrated average based multimoment method, and a continuum surface force model.
Abstract: We numerically investigated liquid droplet impact behavior onto a dry and flat surface. The numerical method consists of a coupled level set and volume-of-fluid framework, volume/surface integrated average based multimoment method, and a continuum surface force model. The numerical simulation reproduces the experimentally observed droplet behavior quantitatively, in both the spreading and receding phases, only when we use a dynamic contact angle model based on experimental observations. If we use a sensible simplified dynamic contact angle model, the predicted time dependence of droplet behavior is poorly reproduced. The result shows that precise dynamic contact angle modeling plays an important role in the modeling of droplet impact behavior.
265 citations
TL;DR: The proposed WLIC (weighed line interface calculation) method can extend the THINC scheme to multi-dimension while maintaining simplicity of implementation and achieve a higher accuracy than the original THinc scheme.
190 citations
TL;DR: The proposed surface force algorithms, especially the level set based curvature interpolation technique, play a key role in numerical simulations of free surface flows with complex interface geometries.
103 citations
TL;DR: In this article, the authors numerically investigate water droplet splashing on a dry, flat and smooth surface and propose a possible mechanism for how the splash (satellite droplets and spikes) gains the vertical momentum component without the roughness based on the dynamic contact angle.
Abstract: We numerically investigate water droplet splashing on a dry, flat and smooth surface. Our numerical framework can reproduce a prompt splash with satellite droplets and spikes at least qualitatively. The numerical results have shown that the dynamic contact angle can trigger a prompt splash without the roughness of a solid surface. We also propose a possible mechanism for how the splash (satellite droplets and spikes) gains the vertical momentum component without the roughness based on the dynamic contact angle.
68 citations
TL;DR: A level set based algorithm of the density-scaled balanced CSF model can reduce spurious currents more than the standard balancedCSF model without using thedensity-scaling when the exact curvature is not given.
66 citations
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TL;DR: In this article, the authors focus on recent experimental and theoretical studies, which aim at unraveling the underlying physics, characterized by the delicate interplay of liquid inertia, viscosity, and surface tension, but also the surrounding gas.
Abstract: A drop hitting a solid surface can deposit, bounce, or splash. Splashing arises from the breakup of a fine liquid sheet that is ejected radially along the substrate. Bouncing and deposition depend crucially on the wetting properties of the substrate. In this review, we focus on recent experimental and theoretical studies, which aim at unraveling the underlying physics, characterized by the delicate interplay of not only liquid inertia, viscosity, and surface tension, but also the surrounding gas. The gas cushions the initial contact; it is entrapped in a central microbubble on the substrate; and it promotes the so-called corona splash, by lifting the lamella away from the solid. Particular attention is paid to the influence of surface roughness, natural or engineered to enhance repellency, relevant in many applications.
994 citations
TL;DR: A comprehensive review of numerical methods and models for interface resolving simulations of multiphase flows in microfluidics and micro process engineering is presented in this paper, where three common approaches in the sharp interface limit, namely the volume-of-fluid method with interface reconstruction, the level set method and the front tracking method, as well as methods with finite interface thickness such as color function based methods and the phase-field method are discussed.
Abstract: This article presents a comprehensive review of numerical methods and models for interface resolving simulations of multiphase flows in microfluidics and micro process engineering. The focus of the paper is on continuum methods where it covers the three common approaches in the sharp interface limit, namely the volume-of-fluid method with interface reconstruction, the level set method and the front tracking method, as well as methods with finite interface thickness such as color-function based methods and the phase-field method. Variants of the mesoscopic lattice Boltzmann method for two-fluid flows are also discussed, as well as various hybrid approaches. The mathematical foundation of each method is given and its specific advantages and limitations are highlighted. For continuum methods, the coupling of the interface evolution equation with the single-field Navier–Stokes equations and related issues are discussed. Methods and models for surface tension forces, contact lines, heat and mass transfer and phase change are presented. In the second part of this article applications of the methods in microfluidics and micro process engineering are reviewed, including flow hydrodynamics (separated and segmented flow, bubble and drop formation, breakup and coalescence), heat and mass transfer (with and without chemical reactions), mixing and dispersion, Marangoni flows and surfactants, and boiling.
378 citations
TL;DR: The present method can preserve the total mass as the Cahn-Hilliard equation, but the calculation and implementation are much simpler than that and the satisfactions of mass conservations are guaranteed.
303 citations
TL;DR: In this paper, a detailed review of the physical processes during 3D printing and the fundamental science of densification after sintering and post-heat treatment steps are provided to understand the microstructural evolution and properties of binder jetted parts.
293 citations
TL;DR: In this article, the authors numerically investigated liquid droplet impact behavior onto a dry and flat surface using a coupled level set and volume-of-fluid framework, volume/surface integrated average based multimoment method, and a continuum surface force model.
Abstract: We numerically investigated liquid droplet impact behavior onto a dry and flat surface. The numerical method consists of a coupled level set and volume-of-fluid framework, volume/surface integrated average based multimoment method, and a continuum surface force model. The numerical simulation reproduces the experimentally observed droplet behavior quantitatively, in both the spreading and receding phases, only when we use a dynamic contact angle model based on experimental observations. If we use a sensible simplified dynamic contact angle model, the predicted time dependence of droplet behavior is poorly reproduced. The result shows that precise dynamic contact angle modeling plays an important role in the modeling of droplet impact behavior.
265 citations