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Yuying Wang - One of the best experts on this subject based on the ideXlab platform.

  • concurrent coupling of Atomistic Simulation and mesoscopic hydrodynamics for flows over soft multi functional surfaces
    Soft Matter, 2019
    Co-Authors: Chao Yang, Yuying Wang, George Em Karniadakis
    Abstract:

    We develop an efficient parallel multiscale method that bridges the Atomistic and mesoscale regimes, from nanometers to microns and beyond, via concurrent coupling of Atomistic Simulation and mesoscopic dynamics. In particular, we combine an all-atom molecular dynamics (MD) description for specific Atomistic details in the vicinity of the functional surface with a dissipative particle dynamics (DPD) approach that captures mesoscopic hydrodynamics in the domain away from the functional surface. In order to achieve a seamless transition in dynamic properties we endow the MD Simulation with a DPD thermostat, which is validated against experimental results by modeling water at different temperatures. We then validate the MD-DPD coupling method for transient Couette and Poiseuille flows, demonstrating that the concurrent MD-DPD coupling can resolve accurately the continuum-based analytical solutions. Subsequently, we simulate shear flows over grafted polydimethylsiloxane (PDMS) surfaces (polymer brushes) for various grafting densities, and investigate the slip flow as a function of the shear stress. We verify that a “universal” power law exists for the slip length, in agreement with published results. Having validated the MD-DPD coupling method, we simulate time-dependent flows past an endothelial glycocalyx layer (EGL) in a microchannel. Coupled Simulation results elucidate the dynamics of the EGL changing from an equilibrium state to a compressed state under shear by aligning the molecular structures along the shear direction. MD-DPD Simulation results agree well with results of a single MD Simulation, but with the former more than two orders of magnitude faster than the latter for system sizes above one micron.

  • concurrent coupling of Atomistic Simulation and mesoscopic hydrodynamics for flows over soft multi functional surfaces
    arXiv: Computational Physics, 2018
    Co-Authors: Chao Yang, Yuying Wang, George Em Karniadakis
    Abstract:

    We develop an efficient parallel multiscale method that bridges the Atomistic and mesoscale regimes, from nanometer to micron and beyond, via concurrent coupling of Atomistic Simulation and mesoscopic dynamics. In particular, we combine an all-atom molecular dynamics (MD) description for specific Atomistic details in the vicinity of the functional surface, with a dissipative particle dynamics (DPD) approach that captures mesoscopic hydrodynamics in the domain away from the functional surface. In order to achieve a seamless transition in dynamic properties we endow the MD Simulation with a DPD thermostat, which is validated against experimental results by modeling water at different temperatures. We then validate the MD-DPD coupling method for transient Couette and Poiseuille flows, demonstrating that the concurrent MD-DPD coupling can resolve accurately the continuum-based analytical solutions. Subsequently, we simulate shear flows over polydimethylsiloxane (PDMS)-grafted surfaces (polymer brushes) for various grafting densities, and investigate the slip flow as a function of the shear stress. We verify that a "universal" power law exists for the sliplength, in agreement with published results. Having validated the MD-DPD coupling method, we simulate time-dependent flows past an endothelial glycocalyx layer (EGL) in a microchannel. Coupled Simulation results elucidate the dynamics of EGL changing from an equilibrium state to a compressed state under shear by aligning the molecular structures along the shear direction. MD-DPD Simulation results agree well with results of a single MD Simulation, but with the former more than two orders of magnitude faster than the latter for system sizes above one micron.

Seunghwa Ryu - One of the best experts on this subject based on the ideXlab platform.

  • the effect of the misfit dislocation on the in plane shear response of the ferrite cementite interface
    Computational Materials Science, 2020
    Co-Authors: Jaemin Kim, Seunghwa Ryu, Hadi Ghaffarian, Keonwook Kang
    Abstract:

    Abstract Although the pearlitic steel is one of the most extensively studied materials, there are still questions unanswered about the interface in the lamellar structure. In particular, to deepen the understanding of the mechanical behavior of pearlitic steel with fine lamellar structure, it is essential to reveal the structure-property relationship of the ferrite/cementite interface. In this study, we analyzed the in-plane shear deformation of the ferrite/cementite interface using Atomistic Simulation combined with extended atomically informed Frank-Bilby method and disregistry analyses. In the Atomistic Simulation, we applied in-plane shear stress along twelve different directions to the ferrite/cementite bilayer for Isaichev, Near Bagaryatsky and Near Pitsch-Petch orientation relationship, respectively. The Simulation results reveal that Isaichev and Near Bagaryatsky orientations show dislocation-mediated plasticity except two directions, while Near Pitsch-Petch orientation shows mode II (in-plane shear) fracture at the ferrite/cementite interface along all directions. Based on the extended atomically informed Frank-Bilby and disregistry analysis results, we conclude that the in-plane shear behavior of the ferrite/cementite interface is governed by the magnitude of Burgers vector and core-width of misfit dislocations.

  • the effect of the misfit dislocation on the in plane shear response of the ferrite cementite interface
    Unknown Journal, 2018
    Co-Authors: Jaemin Kim, Keonwook Kang, Seunghwa Ryu
    Abstract:

    Although the pearlitic steel is one of the most extensively studied materials, there are still questions unanswered about the interface in the lamellar structure. In particular, to deepen the understanding of the mechanical behavior of pearlitic steel with fine lamellar structure, it is essential to reveal the structure-property relationship of the ferrite/cementite interface (FCI). In this study, we analyzed the in-plane shear deformation of the FCI using Atomistic Simulation combined with extended atomically informed Frank-Bilby (xAIFB) method and disregistry analyses. In the Atomistic Simulation, we applied in-plane shear stress along twelve different directions to the ferrite/cementite bilayer for Isaichev (IS), Near Bagaryatsky (Near BA) and Near Pitsch-Petch (Near PP) orientation relationship (OR), respectively. The Simulation results reveal that IS and Near BA ORs show dislocation-mediated plasticity except two directions, while Near PP OR shows mode II (in-plane shear) fracture at the FCI along all directions. Based on the xAIFB and disregistry analysis results, we conclude that the in-plane shear behavior of the FCI is governed by the magnitude of Burgers vector and core-width of misfit dislocations.

  • characterization of the misfit dislocations at the ferrite cementite interface in pearlitic steel an Atomistic Simulation study
    International Journal of Plasticity, 2016
    Co-Authors: Jaemin Kim, Keonwook Kang, Seunghwa Ryu
    Abstract:

    Abstract The characteristics of the misfit dislocations at ferrite/cementite interfaces (FCIs) for various orientation relationships (ORs) have important implications for the mechanical behavior and the phase transformation of pearlitic steels; however, the detailed characteristics of these misfit dislocations have not been thoroughly elucidated to date. Using the extended atomically informed Frank–Bilby (xAIFB) method and Atomistic Simulation, we characterized the structures of misfit dislocations and calculated the interface energies of five ORs (Bagaryatsky, Isaichev, Pitsch–Petch, Near Bagaryatsky and Near Pitsch–Petch), respectively. Atomistic calculations of the interface energies of five ORs reveal that (1) the Isaichev OR has the lowest interface formation energy and (2) Near Bagaryatsky and Near Pitsch–Petch ORs are energetically more favorable than exact Bagaryatsky and Pitsch–Petch ORs in spite of small misorientation angle. The interface formation energy of each OR is qualitatively well explained by the structure and spacing of FCI dislocations, which demonstrate the importance of the characterization of misfit dislocations.

Nanxian Chen - One of the best experts on this subject based on the ideXlab platform.

  • Atomistic Simulation of misfit dislocation in metal oxide interfaces
    Computational Materials Science, 2008
    Co-Authors: Y Long, Nanxian Chen
    Abstract:

    Abstract In this work, we use a Chen–Mobius inversion method to get the interatomic potentials for metal/oxide interfaces, and then study the misfit dislocation in a series of interfaces, including Au/MgO, Rh/MgO and Ni/MgO. The calculation shows that dislocation line always prefers at the first monolayer of metal side, with metal on top of Mg at the dislocation core, and metal on top of O at the interface coherent area. Also, the Burgers vector for these interfaces is determined at two cases. For Rh/MgO and Ni/MgO, it keeps the value of a 2 [ 1 1 0 ] . But for Au/MgO, it changes from a 2 [ 1 1 0 ] to a[1 0 0] as the number of monolayers in metal side increases. This work shows a theoretical understanding of misfit dislocations in metal/oxide interfaces, from dislocation structure, density to Burgers vector orderly, and gives some hints to experiments.

Keonwook Kang - One of the best experts on this subject based on the ideXlab platform.

  • the effect of the misfit dislocation on the in plane shear response of the ferrite cementite interface
    Computational Materials Science, 2020
    Co-Authors: Jaemin Kim, Seunghwa Ryu, Hadi Ghaffarian, Keonwook Kang
    Abstract:

    Abstract Although the pearlitic steel is one of the most extensively studied materials, there are still questions unanswered about the interface in the lamellar structure. In particular, to deepen the understanding of the mechanical behavior of pearlitic steel with fine lamellar structure, it is essential to reveal the structure-property relationship of the ferrite/cementite interface. In this study, we analyzed the in-plane shear deformation of the ferrite/cementite interface using Atomistic Simulation combined with extended atomically informed Frank-Bilby method and disregistry analyses. In the Atomistic Simulation, we applied in-plane shear stress along twelve different directions to the ferrite/cementite bilayer for Isaichev, Near Bagaryatsky and Near Pitsch-Petch orientation relationship, respectively. The Simulation results reveal that Isaichev and Near Bagaryatsky orientations show dislocation-mediated plasticity except two directions, while Near Pitsch-Petch orientation shows mode II (in-plane shear) fracture at the ferrite/cementite interface along all directions. Based on the extended atomically informed Frank-Bilby and disregistry analysis results, we conclude that the in-plane shear behavior of the ferrite/cementite interface is governed by the magnitude of Burgers vector and core-width of misfit dislocations.

  • the effect of the misfit dislocation on the in plane shear response of the ferrite cementite interface
    Unknown Journal, 2018
    Co-Authors: Jaemin Kim, Keonwook Kang, Seunghwa Ryu
    Abstract:

    Although the pearlitic steel is one of the most extensively studied materials, there are still questions unanswered about the interface in the lamellar structure. In particular, to deepen the understanding of the mechanical behavior of pearlitic steel with fine lamellar structure, it is essential to reveal the structure-property relationship of the ferrite/cementite interface (FCI). In this study, we analyzed the in-plane shear deformation of the FCI using Atomistic Simulation combined with extended atomically informed Frank-Bilby (xAIFB) method and disregistry analyses. In the Atomistic Simulation, we applied in-plane shear stress along twelve different directions to the ferrite/cementite bilayer for Isaichev (IS), Near Bagaryatsky (Near BA) and Near Pitsch-Petch (Near PP) orientation relationship (OR), respectively. The Simulation results reveal that IS and Near BA ORs show dislocation-mediated plasticity except two directions, while Near PP OR shows mode II (in-plane shear) fracture at the FCI along all directions. Based on the xAIFB and disregistry analysis results, we conclude that the in-plane shear behavior of the FCI is governed by the magnitude of Burgers vector and core-width of misfit dislocations.

  • characterization of the misfit dislocations at the ferrite cementite interface in pearlitic steel an Atomistic Simulation study
    International Journal of Plasticity, 2016
    Co-Authors: Jaemin Kim, Keonwook Kang, Seunghwa Ryu
    Abstract:

    Abstract The characteristics of the misfit dislocations at ferrite/cementite interfaces (FCIs) for various orientation relationships (ORs) have important implications for the mechanical behavior and the phase transformation of pearlitic steels; however, the detailed characteristics of these misfit dislocations have not been thoroughly elucidated to date. Using the extended atomically informed Frank–Bilby (xAIFB) method and Atomistic Simulation, we characterized the structures of misfit dislocations and calculated the interface energies of five ORs (Bagaryatsky, Isaichev, Pitsch–Petch, Near Bagaryatsky and Near Pitsch–Petch), respectively. Atomistic calculations of the interface energies of five ORs reveal that (1) the Isaichev OR has the lowest interface formation energy and (2) Near Bagaryatsky and Near Pitsch–Petch ORs are energetically more favorable than exact Bagaryatsky and Pitsch–Petch ORs in spite of small misorientation angle. The interface formation energy of each OR is qualitatively well explained by the structure and spacing of FCI dislocations, which demonstrate the importance of the characterization of misfit dislocations.

George Em Karniadakis - One of the best experts on this subject based on the ideXlab platform.

  • concurrent coupling of Atomistic Simulation and mesoscopic hydrodynamics for flows over soft multi functional surfaces
    Soft Matter, 2019
    Co-Authors: Chao Yang, Yuying Wang, George Em Karniadakis
    Abstract:

    We develop an efficient parallel multiscale method that bridges the Atomistic and mesoscale regimes, from nanometers to microns and beyond, via concurrent coupling of Atomistic Simulation and mesoscopic dynamics. In particular, we combine an all-atom molecular dynamics (MD) description for specific Atomistic details in the vicinity of the functional surface with a dissipative particle dynamics (DPD) approach that captures mesoscopic hydrodynamics in the domain away from the functional surface. In order to achieve a seamless transition in dynamic properties we endow the MD Simulation with a DPD thermostat, which is validated against experimental results by modeling water at different temperatures. We then validate the MD-DPD coupling method for transient Couette and Poiseuille flows, demonstrating that the concurrent MD-DPD coupling can resolve accurately the continuum-based analytical solutions. Subsequently, we simulate shear flows over grafted polydimethylsiloxane (PDMS) surfaces (polymer brushes) for various grafting densities, and investigate the slip flow as a function of the shear stress. We verify that a “universal” power law exists for the slip length, in agreement with published results. Having validated the MD-DPD coupling method, we simulate time-dependent flows past an endothelial glycocalyx layer (EGL) in a microchannel. Coupled Simulation results elucidate the dynamics of the EGL changing from an equilibrium state to a compressed state under shear by aligning the molecular structures along the shear direction. MD-DPD Simulation results agree well with results of a single MD Simulation, but with the former more than two orders of magnitude faster than the latter for system sizes above one micron.

  • concurrent coupling of Atomistic Simulation and mesoscopic hydrodynamics for flows over soft multi functional surfaces
    arXiv: Computational Physics, 2018
    Co-Authors: Chao Yang, Yuying Wang, George Em Karniadakis
    Abstract:

    We develop an efficient parallel multiscale method that bridges the Atomistic and mesoscale regimes, from nanometer to micron and beyond, via concurrent coupling of Atomistic Simulation and mesoscopic dynamics. In particular, we combine an all-atom molecular dynamics (MD) description for specific Atomistic details in the vicinity of the functional surface, with a dissipative particle dynamics (DPD) approach that captures mesoscopic hydrodynamics in the domain away from the functional surface. In order to achieve a seamless transition in dynamic properties we endow the MD Simulation with a DPD thermostat, which is validated against experimental results by modeling water at different temperatures. We then validate the MD-DPD coupling method for transient Couette and Poiseuille flows, demonstrating that the concurrent MD-DPD coupling can resolve accurately the continuum-based analytical solutions. Subsequently, we simulate shear flows over polydimethylsiloxane (PDMS)-grafted surfaces (polymer brushes) for various grafting densities, and investigate the slip flow as a function of the shear stress. We verify that a "universal" power law exists for the sliplength, in agreement with published results. Having validated the MD-DPD coupling method, we simulate time-dependent flows past an endothelial glycocalyx layer (EGL) in a microchannel. Coupled Simulation results elucidate the dynamics of EGL changing from an equilibrium state to a compressed state under shear by aligning the molecular structures along the shear direction. MD-DPD Simulation results agree well with results of a single MD Simulation, but with the former more than two orders of magnitude faster than the latter for system sizes above one micron.