*********************************
There is now a CONTENT FREEZE for Mercury while we switch to a new platform. It began on Friday, March 10 at 6pm and will end on Wednesday, March 15 at noon. No new content can be created during this time, but all material in the system as of the beginning of the freeze will be migrated to the new platform, including users and groups. Functionally the new site is identical to the old one. webteam@gatech.edu
*********************************
Pavan Patel
Advisor: Prof. Suresh Menon
will propose a master’s thesis entitled,
Uncertainty Quantification of DIMP Pyrolysis Kinetics
On
Wednesday, May 4th at 11:00 a.m.
Montgomery Knight Building 317
https://bluejeans.com/925588182/7067
Abstract
To develop effective weapons for the rapid destruction of sarin, a reliable understanding of sarin’s chemical kinetics is needed. Kinetic mechanisms of sarin simulants such as di-isopropyl methyl phosphonate (DIMP) are developed instead because they have a similar chemical structure as sarin and are less toxic. A detailed DIMP kinetics mechanism has been developed in the past; however, there is a considerable amount of uncertainty surrounding it. This uncertainty manifests through the choice of pathways, and their respective reaction rates, leading to large variations in outcomes predicted through simulations. Out of the many reaction pathways involved in the decomposition of DIMP, the initiating steps are the most crucial. Two possible initiating pathways were hypothesized previously by researchers based on experimental observations. They proposed the first pathway to be active when the heating rates are below O(104) K/s (low heating rate pathway) and the second pathway to be active when the heating rates are greater than O(104) K/s (high heating rate pathway). Assuming this hypothesis to be true, it is expected that the rate parameters associated with these two initiating pathways correctly model the hypothesis.
The purpose of this study is threefold: first, to verify the postulated hypothesis regarding the initial step; second; to quantify prediction uncertainties caused by uncertainties in the dominant initial decomposition pathway; third, to reduce the uncertainties associated with this pathway such that the variation in predicted outcomes is within reasonable limits.
Using direct numerical simulations (DNS) of a high-energy explosive it was found that the high heating rate pathway does not correctly model the hypothesis i.e., the lower heating rate pathway was found to be dominant even in regions of high heating rate. Furthermore, propagating rate parameter uncertainties of the dominant pathway (the low heating rate pathway) through computational models yields large prediction uncertainties. However, after reducing these rate parameter uncertainties, using Bayesian inference, the prediction uncertainties were within reasonable limits. The results here provide a reduced subspace for uncertainties associated with the first and most important step in the breakdown of DIMP, which shall enable more reliable predictions. More importantly, these results indicate a need for more experimental and theoretical studies aimed at determining the true rate parameters of the high heating rate pathway.
Committee
