Junseok Kim

Bio: Junseok Kim is an academic researcher from Korea University. The author has contributed to research in topics: Numerical analysis & Cahn–Hilliard equation. The author has an hindex of 36, co-authored 262 publications receiving 4578 citations. Previous affiliations of Junseok Kim include Korea Institute of Science and Technology & University of California, Irvine.

Phase-Field Models for Multi-Component Fluid Flows

Abstract: In this paper, we review the recent development of phase-field models and their numerical methods for multi-component fluid flows with interfacial phenomena. The models consist of a Navier-Stokes system coupled with a multi-component Cahn-Hilliard system through a phase-field dependent surface tension force, variable density and viscosity, and the advection term. The classical infinitely thin boundary of separation between two immiscible fluids is replaced by a transition region of a small but finite width, across which the composition of the mixture changes continuously. A constant level set of the phase-field is used to capture the interface between two immiscible fluids. Phase-field methods are capable of computing topological changes such as splitting and merging, and thus have been applied successfully to multi-component fluid flows involving large interface deformations. Practical applications are provided to illustrate the usefulness of using a phase-field method. Computational results of various experiments show the accuracy and effectiveness of phase-field models.

Phase field modeling and simulation of three-phase flows

Abstract: Abstract. In this paper, we derive a thermodynamically consistent pha se-field model for flows containing three (or more) liquid components. The model is based on a Navier-S tokes (NS) and Cahn-Hilliard system (CH) which accounts for surface tension among the different component s a d three-phase contact lines. We develop a stable conservative, second order accurate fully implicit discre tization of the NS and three-phase (ternary) CH system. We use a nonlinear multigrid method to efficiently solve the dis crete ternary CH system at the implicit time-level and then couple it to a multigrid/projection method that is used to solve the NS equation. We demonstrate convergence of our scheme numerically and perform numerical simulation s to show the accuracy, flexibility, and robustness of this approach. In particular, we simulate a three interface contact angle resulting from a spreading liquid lens on an interface, a buoyancy-driven compound drop, and the Rayl eigh-Taylor instability of a flow with three partially miscible components.

Recent advances in 3D printing of biomaterials

Abstract: 3D Printing promises to produce complex biomedical devices according to computer design using patient-specific anatomical data. Since its initial use as pre-surgical visualization models and tooling molds, 3D Printing has slowly evolved to create one-of-a-kind devices, implants, scaffolds for tissue engineering, diagnostic platforms, and drug delivery systems. Fueled by the recent explosion in public interest and access to affordable printers, there is renewed interest to combine stem cells with custom 3D scaffolds for personalized regenerative medicine. Before 3D Printing can be used routinely for the regeneration of complex tissues (e.g. bone, cartilage, muscles, vessels, nerves in the craniomaxillofacial complex), and complex organs with intricate 3D microarchitecture (e.g. liver, lymphoid organs), several technological limitations must be addressed. In this review, the major materials and technology advances within the last five years for each of the common 3D Printing technologies (Three Dimensional Printing, Fused Deposition Modeling, Selective Laser Sintering, Stereolithography, and 3D Plotting/Direct-Write/Bioprinting) are described. Examples are highlighted to illustrate progress of each technology in tissue engineering, and key limitations are identified to motivate future research and advance this fascinating field of advanced manufacturing.

Infinite-Dimensional Dynamical Systems in Mechanics and Physics (Roger Temam)

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A Ghost-Cell Immersed Boundary Method for Flow in Complex Geometry

Abstract: An efficient ghost-cell immersed boundary method (GCIBM) for simulating turbulent flows in complex geometries is presented. A boundary condition is enforced through a ghost cell method. The reconstruction procedure allows systematic development of numerical schemes for treating the immersed boundary while preserving the overall second-order accuracy of the base solver. Both Dirichlet and Neumann boundary conditions can be treated. The current ghost cell treatment is both suitable for staggered and non-staggered Cartesian grids. The accuracy of the current method is validated using flow past a circular cylinder and large eddy simulation of turbulent flow over a wavy surface. Numerical results are compared with experimental data and boundary-fitted grid results. The method is further extended to an existing ocean model (MITGCM) to simulate geophysical flow over a three-dimensional bump. The method is easily implemented as evidenced by our use of several existing codes.