Abstract : Focus of this mini-symposium will be on the modelling and computational aspects of multiscale coupling strategies and hybrid techniques -continuum, mesoscopic, atomistic- specifically applied to complex fluids, such as colloidal suspensions, granular media, polymeric systems and/or multiphase flows. The goal is, on one hand, to share state-of-the-art results on multiscale approaches in fluids, on the other to discuss technical issues on their computational modelling. We believe that this mini-symposium will foster new collaborations and contribute to further advances in the field.
Organizer(s) : Giulio Giusteri, Takashi Taniguchi, Marco Ellero
[05277] Multi-Physics Simulations of Flow, Friction, and Reactions in Solid/Liquid Interface
Format : Talk at Waseda University
Author(s) :
Momoji Kubo (Tohoku University)
Abstract : In recent years, due to strong demands for energy saving and carbon neutrality, maximizing energy utilization efficiency in automobiles, airplanes, etc. is required. Therefore, it is essential to establish the technologies for the super-low friction. In the present study, we employed our supercomputer “MASAMUNE-IMR” and successfully applied our large-scale molecular dynamics code “Laich” to clarifying the multi-physics processes of the flow, friction, and chemical reactions in the solid/liquid interfaces for realizing the super-low friction system.
[02346] Numerical modeling of viscoelastic flows with high elasticity
Format : Talk at Waseda University
Author(s) :
Laura Moreno (Universita degli Studi di Padova)
Joan Baiges (Universitat Politecnica de Catalunya)
Ramon Codina (Universitat Politecnica de Catalunya)
Abstract : Computing the viscoelastic fluid flow involves a wide range of difficulties, in particular when elasticity becomes dominant. These difficulties are considered one of the biggest challenges in computational rheology; this is known as the High Weissenberg Number Problem.This work presents different strategies to deal with the shortcomings that appear when the fluid is particularly elastic. These are carried out in the Finite Element framework and by using the Variational Multiscale formulation as a stabilization approach.
[02354] DPD Simulation of Ultrasound Propagation through Liquid Water
Format : Talk at Waseda University
Author(s) :
Petra Papež (National Institute of Chemistry, Ljubljana)
Matej Praprotnik (National Institute of Chemistry, Ljubljana)
Abstract : We present a dissipative particle dynamics simulation of ultrasound propagation through liquid water. The effects of frequency and thermostat parameters are studied and discussed. We show that frequency and thermostat parameters affect not only the attenuation but also the computed speed of sound. The present study paves the way for development and optimization of a virtual ultrasound machine for large-scale biomolecular simulations.
[04595] Machine-Learning for Accelerated Multi-Scale Polymer Flow Simulations
Format : Talk at Waseda University
Author(s) :
John Jairo Molina (Kyoto University)
Souta Miyamoto (Kyoto University)
Yoshiki Ueno (Kyoto University)
Takashi Taniguchi (Kyoto University)
Abstract : We develop a Bayesian Machine-Learning approach, based on a Gaussian Process Regression, to accelerate Multi-Scale Simulations (MSS) of polymer melt flows. In particular, we are able to learn the constitutive relation of entangled polymer melts (within the Doi-Takimoto model), which are then used within macroscopic flow solvers, drastically reducing the computational cost. We also show how ML can be used to reduce the statistical variance of a full MSS, significantly enhancing its computational efficiency.
[03437] Simulation of micro-scale particulate motion in gases
Format : Talk at Waseda University
Author(s) :
Duncan Lockerby (University of Warwick)
Josiah Jordan (University of Warwick)
Abstract : Low-speed gas flow around micro-scale particles (e.g. soot and other pollutants), and through suspensions of particles, are rich in physics and challenging to simulate. The hydrodynamic reach of a single particle is broad, making application of conventional approaches (e.g. finite-volume CFD) computationally expensive. Furthermore, their scale renders the conventional Navier-Stokes equations, and associated boundary conditions, inaccurate. In this talk we discuss recent developments in simulating micro-scale particulate flows using the Method of Fundamental Solutions.
[03686] Synchronized Molecular-Dynamics simulation of the thermal lubrication of an entangled polymer melt
Format : Talk at Waseda University
Author(s) :
Shugo Yasuda (University of Hyogo)
Abstract : The thermo-rheological property of an entangled polymer melt in wall-driven shear flows is investigated by using a multiscale hybrid method, coupling molecular dynamics and hydrodynamic. The temperature of the polymeric liquid rapidly increases due to viscous heating once the drive force exceeds a certain threshold value, and the rheological properties drastically change at around the critical drive force. A remarkable observation is the re-entrant transition in the stress–optical relation at this threshold point.
[03368] Simulation of multiphase flows based on Lagrangian methods
Format : Talk at Waseda University
Author(s) :
Xin Bian (Zhejiang University)
Abstract : We study dynamics of a solid particle, a droplet, a vesicle, and a red blood cell (RBC) suspended in a Newtonian fluid, respectively. These four systems share common features, while distinct behaviors are also very apparent. We employ the smoothed particle hydrodynamics (SPH) method to solve the matrix fluid universally, but deal with the suspended object differently. We investigate their rich behaviors in Couette/Poiseuille flows.
[03717] Lagrangian Heterogeneous Multiscale Methods: A generalized multiphysics model for complex fluids with memory
Format : Talk at Waseda University
Author(s) :
Nicolas Moreno (Basque Center for Applied Mathematics)
Marco Ellero (Basque Center for Applied Mathematics)
Abstract : We present a Lagrangian multiscale/multiphysics framework for modeling complex fluids in various flow configurations. Our method employs Smoothed Dissipative Particle Dynamics (SDPD) to model fluids at both micro and macro scales, allowing us to incorporate complex physical models such as polymer solutions and multiphase flows. The method accurately captures stresses and enables the simulation of mixed flows. We validate the framework with benchmark configurations for Newtonian and non-Newtonian fluids, demonstrating its effectiveness in modeling complex fluids at both scales. Our methodology provides a natural link between macro and microscales and accounts for memory effects, resulting in a richer fluid response at the continuum.
[05555] Moisture-induced weakening of adhesion between polymers and metals
Format : Talk at Waseda University
Author(s) :
Shuji Ogata (Nagoya Institute of Technology)
Abstract : Adhesive bonding has attracted renewed interest from the manufacturing industry due to its role in creating composite materials and multimaterial designs with the desired arrangements of polymers and metals. In the present work, we theoretically addressed a fundamental problem of the moisture-induced adhesion weakening between polymers (or resin) and metal from a novel viewpoint of (de)protonation of them in water.
[03509] Modelling and Simulation of Capillary Origami in Three Dimensions
Format : Talk at Waseda University
Author(s) :
Zhixuan Li (National University of Singapore)
Weiqing Ren (National University of Singapore)
Abstract : Capillary origami involves folding a planar object into a 3D structure using capillary force, and has many important applications such as the fabrication of microelectromechanical systems. In this work, we propose a three-dimensional model of the droplet-on-sheet system with a pinned contact line. The system energy consists of interfacial energies caused by surface tensions and the elastic energy of the thin sheet given by nonlinear Koiter's model. We derive the governing equations of the static equilibrium using a variational approach. We then propose a numerical algorithm to find the equilibrium via a relaxation dynamics. We use the subdivision element method for discretization of the sheet, which provides $C^1 \cap H^2$ basis functions, and a modified area-minimizing functional for maintaining the mesh quality of the discrete droplet surface. Our numerical simulations demonstrate first-order and second-order convergence in time and space, respectively, and are in good agreement with physical experiments. Specifically, for a triangular sheet, we present phase diagrams of folding, which exhibit rich and fully three-dimensional behaviors not captured by previous two-dimensional models. Our results provide new insights into the mechanics of capillary folding and can inform the design of microfabrication techniques.
[04590] Multiscale simulation of a polymer melt flow between two coaxial cylinders under nonisothermal conditions
Format : Talk at Waseda University
Author(s) :
Takashi Taniguchi (Kyoto University)
Takeshi Sato (Kyoto University)
Yuji Hamada (Kyoto University)
Abstract : We successfully extend a multiscale simulation (MSS) method to nonisothermal wellentangled
polymer melt flows between two coaxial cylinders. In the multiscale simulation, the
macroscopic flow system is connected to a number of microscopic systems through the velocity
gradient tensor, stress tensor and temperature. At the macroscopic level, in addition to the momentum
balance equation, we consider the energy balance equation, where heat generation plays an important
role not only in the temperature distribution but also in the flow profile.
[05592] Flow-type dependent rheologies and multiscale simulations
Format : Talk at Waseda University
Author(s) :
Giulio Giuseppe Giusteri (University of Padua)
Francesca Tedeschi (University of Padua)
Maria Lukácová-Medvid'ová (Johannes Gutenberg University of Mainz)
Leonid Yelash (Johannes Gutenberg University of Mainz)
Abstract : The importance of taking into consideration the dependence on the local flow type of the response of non-Newtonian fluids in multiscale data-driven simulations will be highlighted. A framework to organize data in mixed flows and reconstruct the stress tensor will be reviewed. Then, an algorithm to take into account the flow-type dependence in a consistent way will be presented by discussing paradigmatic planar flows implied by data obtained with a FENE-type model for polymer chains.
