Multiscale Modeling of High Energy-Density Environments: Two Approaches
报告题目：Multiscale Modeling of High Energy-Density Environments: Two Approaches
报 告 人：Professor Michael S. Murillo
Department of Computational Mathematics, Science and Engineering
Michigan State University
报告简介：High energy-density experiments are notoriously expensive, challenging to control and difficult to diagnose, placing an extra burden on our computational ability to design and interpret them. While the standard methodology of employing hydrodynamics models with accurate equations of state has proven enormously useful, high-temperature systems are subject to a variety of non-hydrodynamic features, including non-Maxwellian velocity distributions, multispecies (potentially non-local) transport and mixing, and electromagnetic fields. To address these issues, we are developing new multiscale methods; two variants will be presented here for scope and contrast. The first is a multiscale model within a single method, in our case molecular dynamics (MD). In this new method, we break the electronic structure problem into three scales, each of which is treated with fast methods that account for the symmetries at each scale. We have implemented this model with an orbital-free density functional theory approach (currently finite-temperature Thomas-Fermi) and have simulated interfacial mixing of an inertial-confinement fusion scenario using MD with 57.6 million particles. The results are used to examine the breakdown of the hydrodynamic description for this scenario. Unfortunately, the time and length scales that are required do not allow us to employ even the fastest MD algorithms. For such scales, we have developed a heterogeneous multiscale method (HMM) specifically for the high energy-density regime. In this method, we employ MD for the microscale method and a new Vlasov-BGK model for the macroscale method; again, we are able to exploit symmetries to reduce computational costs. A surprising number of subtle issues in non-equilibrium statistical mechanics emerge for such a kinetic HMM model, and these issues will be briefly mentioned.
报告人简介：Prof. Michael S. Murillo received his PhD degree in Physics from Rice University in 1995. Later, he accepted the Director’s Fellowship of Los Alamos National Laboratory (LANL), working in dense plasma physics and molecular dynamics techniques. In 1997, he became a Technical Staff Member at LANL, where he served in several roles, including a Project Leader in the Advanced Scientific Computing Program and the Team Leader for High Energy-Density Physics. In 2009, he was selected as the APS Fellow with the citation of “For original theoretical and computational research in several areas of non-ideal plasmas, including non-equilibrium properties of ultra-cold plasmas, collective properties of dusty plasmas, transport in strongly coupled plasmas, and atomic physics in dense plasmas.” He went to Michigan State University in 2016. He has already published > 70 papers, including 8 papers on Phys. Rev. Lett., with > 2000 citations, and an h-index of 50 (from Google Scholar).