Plenary and Semi-Plenary Lectures
Click here to return to the list of invitees
| Title: |
| Multiscale Modeling and Simulations of Micro- and Nano-Fluidics |
| Lecturer: |
| Shiyi Chen |
| Abstract: |
Studies of fluid transport in micro- and nano-systems have recently received great attention due mainly to the modern development of micro- and nano-technologies. As the spatial scales of the flow approach the molecular size, the continuum assumption breaks down and the molecular effects cannot be ignored. Atomistic descriptions cannot treat large domains due to the immense number of computational molecules involved and the multiscale simulation capable of coupling molecular dynamics with the continuum hydrodynamics is an efficient way to model the micro- and nano-fludics.
A framework for continuum and molecular dynamics hybrid multiscale method has been recently developed to simulate micro- and nano-fluid flows. The continuum Navier-Stokes equation is used in one flow region and atomistic molecular dynamics in another. The spatial coupling between two methods is achieved through the constrained dynamics in an overlap region.
The proposed multiscale method has been validated in simple fluid flows, including sudden-start Couette flow and channel flow with nano-scale wall roughness, showing quantitative agreement with results from analytical solutions and full molecular dynamics simulations. The hybrid method is then used to study the singularity problem in the driven cavity. Continuum equations predict an infinite force due to stress singularity. Following the stress over more than six decades in length in systems with characteristic scales of millimeters and milliseconds allows us to resolve the singularity and determine the force for the first time. The speedup over pure atomistic calculation is more than fourteen orders of magnitudes. We find a university dependence on the macroscopic Reynolds number, and large atomistic effects that depend on wall velocity and molecular interactions.
The numerical algorithms pertinent to multiscale time and fast convergence to steady states will be presented. Applications of the multiscale method for moving contact lines, polymeric flows, thermal flows and electrokinetic flows will be discussed. |
 Shiyi Chen obtained his Ph.D at Peking University, China in 1987. He worked at Los Alamos National Laboratory as a post-doctoral fellow and Oppenheimer Fellow. He joined Theoretical Division at Los Alamos in 1990 as a research staff member. In 1994, he became a research staff member at the Department of Physical Sciences of IBM T. J.Watson Research Center. From 1997 to 1999, he served as the Deputy Director of the Center for Nonlinear Studies at Los Alamos National Laboratory. Since 1999, he has been a Professor in the Department of Mechanical Engineering and the Department of Mathematical Sciences at the Johns Hopkins University. He served as the Chair from 2002 to 2004 in the Department of Mechanical Engineering at Hopkins. He is currently the Dean of the College of Engineering at Peking University, People’s Republic of China Chen is a Fellow of APS, a Fellow of Los Alamos National Laboratory and a Fellow of IOP. His research interests include multiscale computation and modeling, theory and computation of fluid turbulence, lattice Boltzmann methods, computational fluid dynamics, numerical analysis, nonlinear dynamics, applied mathematics and large scale computing. Chen has published over 140 scientific papers. |
|
|
