Localized Scale Coupling and New Educational Paradigms in Multiscale Mathematics and Science

Lisa Mondy, randy Schunk, and Frank Van Swol

Project Purpose

• Develop robust numerical simulation capabilities for particle-liquid flows that incorporate effects spanning diverse time and length scales.
• Couple micro/nanoscale and mesoscale (particle-size scale) simulations
• Use these simulations to understand physics of bulk suspensions, elucidate conditions when substructuring is needed, determine appropriate boundary conditions, and better represent suspensions with continuum level models for large-scale computations.
• Explain mysteries of two-phase flows!

Stochastic Rotational Dynamic representation of solvent surrounding particles

Technical Approach

• Work closely with LANL, UCSB, UNM
• Couple micro/nanoscale and mesoscale (particle-size scale) simulations – two-pronged approach
  • Include hydrodynamic forces in particle methods
  • Include interparticle molecular forces in hydrodynamic solvers with “patch” elements
• Determine when this level of detail is needed and use substructuring to simulate macroscale (continuum) phenomena

Technical Accomplishments

• Coupled coarse grain molecular solvent representation (Stochastic Rotation Dynamics) to mesoscale (particle-level) Newton’s equation engine (LAAMPS)
• Used Boundary Element Method at mesoscale to determine mechanism of suspension bulk behavior and particle migration observed [Physics of Fluids (submitted)]
• Used molecular dynamics to determine hydrodynamic forces between particles at a molecular scale [Int. J. Multiscale Comp. Eng. (in press)] for element “patch”
• Demonstrated the influence of microstructure on slip at solid-liquid interfaces for better understanding of boundary conditions [I. J. Multiscale Comp. Eng. (in press)]
• Determined ability of continuum equation to model particle sedimentation  [Int. J. Num. Methods in Fluids (in press)]

Importance to ASCR, DOE, SNL

• DOE applications require interplay of small particles and concentrated systems which have never been modeled successfully.
• Increased fundamental understanding of structure-property-processing relationships to support mission-critical DOE applications including multiphase flows for energy production and emerging nanotechnologies.
• New algorithms/approaches for other multiscale and multiphase problems

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