Molecular Dynamics Simulation of Ultra-thin Confined Films and Nano-rheology of Polymeric Systems
Our research interests involve the study of nano-mechanical properties of confined lubricant films, rheology of polymeric systems and crystallization process. We are studying the fundamental physical nature of friction with application in the lubrication of nano-mechanical devices. These films have very rich properties that often deviate from hydrodynamic lubrication and continuum mechanics. The lubrication and rheology of these molecularly thin films are very complex and exhibit exotic behavior such as viscosity enhancement by many orders of magnitude and solidification of the film with intermittent stick-slip behavior. Studying these films have important ramification on understanding the origin of friction and also industrial applications in nanotechnology. The results of our research have applications in many areas such as, lubrication of nano/micro mechanical devices, tribology, rheology and polymer processing. Due to the nature of the problems that we are investigating first principle methods of molecular dynamics are employed in our simulations. These simulations require significant computational power that grows as O(N2) with the number of atoms in the system.
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Principal Investigator Ahmad JabbarzadehSchool of Aerospace, Mechanical and Mechatronic Engineering University of Sydney |
Project k20 |
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Co-Investigators Peter HarrowellDept of Chemistry University of Sydney Roger Tanner Jim Prentzas School of Aerospace, Mechanical and Mechatronic Engineering University of Sydney |
RFCD Codes 290501, 291401, 291804 |
Significant Achievements, Anticipated Outcomes and Future Work
The APAC facility was mainly used for molecular dynamics simulation of ultra-thin films of lubricant and, polymeric and complex systems. Our research was involved the study of nano-mechanical properties of confined lubricant films and their rheology. We were studying the fundamental physical nature of friction with application in the lubrication of nano-mechanical devices. These films have very rich properties that often deviate from hydrodynamic lubrication and continuum mechanics. In year 2005 we reported some of our results the highly prestigious journal of Physical Review Letters [1]. We did a significantly important study on the nature and mechanism of transition to high rigidity of dodecane films, the result of this research was also reported in a paper that was accepted by Physical Review Letters and will appear in the June 2006 issue [2]. Another important study was conducted on the effect of the confining surface atomic in- plane order on the rheology of the lubricant film. The results of this work were reported in a paper that is accepted by Journal of Chemical Physics for publication [3]. We had two other papers that will be published in Rheology Reviews and Australian Journal of Mechanical Engineering [4, 5].
Computational Techniques Used
We used the APAC to run our molecular dynamics simulations using the algorithms developed by one of us (Jabbarzadeh). Although the algorithm was designed to do parallel computations using PVM, most of the simulation were run as single processor jobs. The reason was that using PVM on ALTIX was considered uneconomical due to its communication deficiencies that did not use the internal fast commutation of the system. We are planning to modify our code by implementing MPI, and meanwhile have relied mostly on “lc” for our computations.
In year 2005 we were allocated time at the middle of the year for the third and fourth quarters and we were able to start efficient use of the system at the last quarter for which we used up all the allocated time. In the last round of the resource allocation application for year 2006 we were allocated only 5000 unit of cpu time for each quarter, versus the originally applied 25000. We used up the allocated time in the first month and we had to rely on other resources when we need it the most. Currently we have employed a new postdoc for our project and more resources will be needed once he starts doing the computations. We will appreciate if you could increase the time allocation for our project.
Publications, Awards and External Funding
External Funding and Awards
Our project in year 2005 was funded by an ARC Discovery grant.
Publications
Papers Published or in process of Publication: