A5012057925- Rheology and Fluid Dynamics Studies
- Material Dynamics and Properties
- Polymer crystallization and properties
- Block Copolymer Self-Assembly
- Polymer Nanocomposites and Properties
- Lattice Boltzmann Simulation Studies
- Force Microscopy Techniques and Applications
- Surface Modification and Superhydrophobicity
- Theoretical and Computational Physics
- Fluid Dynamics Simulations and Interactions
- Enhanced Oil Recovery Techniques
- Advanced Polymer Synthesis and Characterization
- Microstructure and mechanical properties
- Protein Structure and Dynamics
- Quantum many-body systems
- Polymer Surface Interaction Studies
- Fusion materials and technologies
- Polymer composites and self-healing
- Computer Graphics and Visualization Techniques
- Fluid Dynamics and Heat Transfer
- Hydrogels: synthesis, properties, applications
- Surfactants and Colloidal Systems
- Physics of Superconductivity and Magnetism
- Advanced Mathematical Modeling in Engineering
- Polymer Foaming and Composites
Tohoku University
2015-2025
Tohoku University Hospital
2019
Japan Science and Technology Agency
2008-2013
Sendai University
2013
Kyoto University
2010-2012
Kyoto Katsura Hospital
2011-2012
Kyushu University
2005-2007
For the purposes of long-term use tungsten divertor walls, formation process fuzzy nanostructure induced by exposure to helium plasma was studied. In present paper, nanostructure's has been successfully reproduced new hybrid simulation method in which deformation material due pressure bubbles simulated molecular dynamics and diffusion atoms random walk based on Monte Carlo method. By results, surface height increased only when retention under steady state. It proven that growth brought about...
Abstract This study aims to develop a multiscale bridging method for investigating nanocrystalline metals based on macro-scale deformation. For this purpose, we propose hierarchical computational that can focus some of the elements in finite element model scale atomistic-scale models. assumes models are related integration points and deform Nanocrystalline aluminum was chosen validation method. The (FEM) molecular dynamics (MD) were used continuum-scale simulations, respectively. We utilized...
Large-scale coarse-grained molecular dynamics simulations of inhomogeneous gel networks were performed to investigate abnormal butterfly patterns in two-dimensional scattering. The diamond lattice-based with distributions the number beads between crosslink points. Remarkably, results confirm that pattern orig-inates from stronger inhomogeneity. For examined systems, range scattering wavevector q for normal was markedly different those patterns. findings address an essential aspect...
Threading of a linear chain through ring has been known to have strong effect on slowing the dynamics ring. To enhance toughness soft materials using ring–linear polymer blends, it is important understand effects parameters such as average squared radius gyration (⟨Rg2⟩) rings, number chains penetrating (nP), and nP dependence shape indexes fraction fring. Using Kremer–Grest model for flexible chains, we simulated rings length Nring = 70 140 0.2 ≤ fring 0.97. The exponent α relation ⟨Rg2⟩ ∝...
Viscosity overshoot of entangled polymer melts has been observed under shear flow and uniaxial elongational but never biaxial flow. We confirmed the presence viscosity flows in a mixed system ring linear polymers expressed by coarse-grained molecular dynamics simulations. The was found to be more pronounced weakly melts. Furthermore, threshold strain rate ε̇th distinguishing nonlinear behaviors dependent on chain length as ε̇th(N) ∼ N–1/2, which differs from conventional relationship, N–2,...
We have developed a new multiscale simulation technique to investigate history-dependent flow behavior of entangled polymer melt, using smoothed particle hydrodynamics with microscopic simulators that account for the dynamics polymers acting on each fluid element. The is applied melt around circular obstacle in two-dimensional periodic system. It found strain-rate stress affects its behavior, and memory causes nonlinear even regions where ${\rm Wi} \le 1$. spatial distribution entanglements...
We have developed a simulation technique of multiscale Lagrangian fluid dynamics to tackle hierarchical problems relating historical dependency polymeric fluid. investigate flow dilute by using the approach incorporating particle (the modified smoothed hydrodynamics) with stochastic coarse-grained polymer simulators dumbbell model). confirmed that our is nicely in agreement macroscopic results obtained constitutive equation corresponding model, and observed microscopic thermal fluctuation...
In this study, we use a coupled finite element method (FEM)–molecular dynamics (MD) methodology to examine the complex deformation response at fine and coarse scales of carbon dioxide hydrate pellets. While previous studies in area have focused on simple deformations fine-scale structures using MD simulations, none attempted model stability pellets under deformations. To accurately represent geometry pellets, employ FEM these cylindrical shapes extract gradients each integration point....
The synergistic mechanisms of chemical interactions and mechanical interlocking in polymer–inorganic material adhesions are important; however, separating evaluating these is challenging. Therefore, this study, a surface model inspired by river meander curves─a type mathematical curve─was constructed to perform coarse-grained molecular dynamics (CGMD) simulations cross-linked polymers adhering channel-patterned surfaces with cooperatively adhesive forces originating from nonbonding pair...
The rheological properties of polycatenanes were investigated by coarse-grained molecular dynamics simulations using the Kremer–Grest-type bead-spring model. To prevent combination number from explosively increasing, systematic structural models [n]catenanes (n = 2, 3, and 4) generated a mathematical graph representation. It was confirmed that behavior storage loss moduli, G′(ω) G″(ω), respectively, depends approximately on beads (monomer units) per catenane at low frequencies. We found...
Multiscale simulation methods have been developed based on the local stress sampling strategy and applied to three flow problems with different difficulty levels: (a) general of simple fluids, (b) parallel (one-dimensional) polymeric liquids, (c) (two- or three-dimensional) liquids. In our multiscale methods, each fluid element is calculated directly by performing microscopic mesoscopic simulations according quantities instead using any constitutive relations. For fluids (a), such as...
Polymer melts exhibit flow-history-dependent behavior. To clearly show this behavior, we have investigated the flow behavior of an entangled polymer melt around two cylinders placed in tandem along direction a two-dimensional periodic system. In system, states cylinder on downstream side differ from those upstream because former memory strain they experienced when passing but latter no such memory. Therefore, shear stress distributions are found to differ. Moreover, that mean velocity...
We investigated the elongational flows of weakly entangled linear polymer melt using a coarse- grained molecular dynamics simulation. extended uniform extensional flow (UEF) method developed by Nicholson and Rutledge (D. A.Nicholson G. C. Rutledge, J. Chem. Phys., 145 244903 (2016)) for application to Langevin dynamics. succeeded in observing viscosity from equilibrium state steady UEF method, whereas conventional rectangular parallelepiped shape technique has failed do so over 20 years.
To develop durable composite materials, it is crucial to elucidate the correlation between nanoscale damage in thermosetting resins and degradation of their mechanical properties. This study aims investigate this by performing cyclic loading tests on cross-linked structure diglycidyl ether bisphenol A (DGEBA) 4,4′-diaminodiphenyl sulfone (44-DDS) using all-atom molecular dynamics (MD) simulations. accurately represent MD simulations, a bond dissociation algorithm based interatomic distance...
We performed all-atom molecular dynamics simulations on poly(ethylene glycol) (PEG) hydrogels to microscopically confirm the recently discovered "negative energetic elasticity" [Y. Yoshikawa et al., Phys. Rev. X 2021, 11, 011045], which refers a negative contribution elastic modulus. To scrutinize force field parameters, we evaluated densities of aqueous solutions linear PEG chains at varying concentrations through and compared them with experimental values. simulated network consisting 23...