CISM • International Centre for Mechanical Sciences

Multiscale Modeling of Flowing Soft Matter and Polymer Systems

Advanced Courses

Soft materials such as polymer melts or solutions, colloidal suspensions, emulsions, foams and gels are materials lying at the interface between fluids and solids requiring, for their simulation, highly innovative computational methods. In a similar way, simulation of fluid flows in nanoscale geometries also needs to account for the molecular nature of the fluid while at the same time retrieving hydrodynamic properties.
This advanced school aims at covering the theory and practice of multiscale modeling of these materials (and the corresponding chemical processes involved) and is specifically addressed to graduate students in physics, chemistry and engineering (chemical, mechanical, environmental, computational) and to scientists and engineers already working in the field. Particular attention will be paid to full-atom and coarse-grained molecular dynamics, dissipative particle dynamics, hybrid molecular/continuum methods, and computational fluid dynamics. Some lectures will focus on molecular dynamics, which is currently used for the estimation of equilibrium (thermodynamic) and non-equilibrium (transport) properties of complex systems. These simulations can employ models with all the structural details of the chemical system (called full-atom) or with only few of them (known as coarse-grained models). Molecular Dynamics treats the atoms as classical objects following Newtonian dynamics, but relies on information obtained from quantum chemistry, which will be also covered in this advanced school. Force fields (employed in molecular dynamics) and many other important properties (such as partial/net atomic charges) are often derived from quantum chemistry calculations, which are also useful for the estimation of chemical reaction rates.
As the chemical complexity of the new materials increases it becomes necessary to develop rapid methods to parametrize reasonably accurate atomistic force fields. In selected applications, e.g. soft materials for electronics, the microstructure and dynamics of the material influences its electronic structure, i.e. one needs larger scale simulations to understand smaller scale properties.
With these modeling techniques, the size of the simulated systems is very limited; the simulation of larger systems requires the use of further coarse-graining, or hybrid methods, that link molecular to hydrodynamic models. Among the different techniques available at these larger time- and length-scales, dissipative particle dynamics, certain hybrid methods, and computational fluid dynamics will be covered. Some lectures will describe the extension of these methods to the simulation of multiphase systems and will discuss some of the numerical issues related to the solution of the governing equations with the finite volume method. Finally, some applications related to the simulation of polymer self- assembly in solution and polymer foam expansion and evolution will be described.


This course is part of the dissemination activities of a project funded by the European Commission under the grant agreement number 604271 (Project acronym: MoDeNa; call identifier: FP7-NMP-2013-SMALL-7). More information about the MoDeNa project can be found at the following link:
http://www.modenaproject.eu/

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Michael Allen (None)
6 lectures on: Full-atom molecular dynamics.
Theoretical background: basic statistical mechanics, static and dynamical properties. Methodology: periodic boundary conditions, the MD algorithm, forcefields. Applications: sampling different ensembles, thermostats and barostats, molecular dynamics of fluid flow and nonequilibrium behaviour.


Paola Carbone (None)
6 lectures on: Coarse-grained molecular dynamics.
Theoretical background/methodology: scalability of the molecular dynamics algorithm, methods of reducing degrees of freedom in a molecular model (bottom-up and top-down approaches). Systematic coarse-graining: structural and thermodynamic techniques), how to tune the degree of coarse-graining and develop atomistic and coarse-grained models. Applications: modeling of soft matter (polymers and surfactants) and simple solutions.


Daniele Marchisio (None)
4 lectures on: Continuum modeling of single phase and multiphase flows.
Theoretical background: link between the molecular and the continuum descriptions: Liouville, Boltzmann and Navier-Stokes equations. Methodology: numerical and computational aspects (finite-volume method). Applications: Simulation of polyurethane foams (and other polymer systems) with the multiscale modelling platform MoDeNa.


Ignacio Pagonabarraga (None)
6 lectures on: Dissipative particle dynamics.
Theoretical background/methodology: mesoscopic simulations of heterogeneous materials and their applications on complex fluids. Formulation of thermodynamically consistent mesoscopic models with appropriate hydrodynamic behaviour. Relationship between dissipative particle dynamics and other coarse grained, hydrodynamically consistent particle-based methods.


Jason Reese (None)
6 lectures on: Continuum/multiscale modeling of fluids.
Hybrid particle/fluid solvers: domain-decomposition vs heterogeneous methods, sequential vs concurrent methods. Coupling methods for time advancement of multiscale dynamic systems. Higher-order hydrodynamic approaches for gas flows. Engineering applications: micro-jet actuators, water flowing carbon nanotubes, thermally-driven gases, etc.


Henrik Rusche (None)
2 lectures on: Multiscale modelling with the MoDeNa platform.
Theoretical background: multiscale modelling, scale coupling, forward and backward coupling, surrogate models, recipes and adapters. Methodology: description of the workflow, orchestrator, database and interface library. Applications: demonstration of the MoDeNa platform for the simulation of poyurethane foams.


Alessandro Troisi (None)
6 lectures on: Quantum chemistry for and from classical simulations.
One-electron approximation, variational principle and basis sets, Har-tree Fock and DFT methods. Computable properties. Procedures to generate classical force fields from electronic structure calculations. Force matching approaches. Application to organic electronics.