Reactive Flow Simulation Using An Adaptive Chemistry Framework

ABSTRACT

PI: Ioannis P. Androulakis and Marianthi Ierapetritou

Institution: Rutgers University

Proposal Number: 0730582

Title: Reactive Flow Simulation Suing an Adaptive Chemistry Framework

The simulation of reactive systems requires efficient and reliable models that provide full coupling of all relevant physical processes and chemistry. Although there is a dramatic increase in recent years in the use of comprehensive computational fluid dynamics tools to model reactive systems, current frameworks cannot afford the incorporation of detailed chemistry. Of particular importance is the analysis of combustion systems due to the fact that approximately 85% of the energy consumed in the United States each year is generated from the combustion of fossil fuels, with transportation being a major contributor. Despite improvements, combustion is responsible for significant amounts of NOx, CO, CO2, and many other chemical species that are considered critical for affecting climate change and air pollution. Advances in computational power offer an opportunity to improve fundamental understanding of combustion at the molecular level so as to improve the energy use in transportation systems. Interactions between multiphase flow, complex chemical kinetics and hydrodynamic turbulence mixing all combine to characterize the combustion process. The main objective of this work is to develop an efficient adaptive chemistry framework that enables the effective coupling of realistic flow calculations with detailed chemistry. The work will focus on combustion systems; however, the tools that will be developed can be extended to any complex reactive systems.

Intellectual Merit: The PIs had previously demonstrated that the development of an adaptive chemistry framework, that captures the local behavior with great accuracy while still maintaining computational feasibility, can provide the missing link between detailed chemistry and flow models. Here they plan an extension of this approach to realistic systems. The target is a methodology that can be used for process simulation, fuel characterization, but most importantly for the design and optimization of novel reactive systems. In particular there are three specific aims. The first aim is the development of a two step reduction procedure where at the first step the idea of element flux analysis is used to identify the key reaction pathways with minimal effort whereas at the second step the optimum reduced reactions sets are identified using an optimization based framework. The identification of the range of validity for the reduced reaction sets and the efficient representation of the accessible region is the focus of the second specific aim. This is of critical importance in order to enable the proper selection of active reduced mechanisms within the flow simulation. They plan two approaches for characterizing the space of accessible points. The first method associates each reduced mechanism with a set of active reaction paths which are represented as graphs, whereas the second method keeps track of all compositions, temperature and pressure and uses novel methods of search in high dimensions to identify the relevant reduced mechanisms. The completion of these two tasks gives rise to a library of reduced sets and the strategy for adaptively witching between reaction sets. A framework that integrates flow calculations with adaptive chemistry will be validated using models of increased complexity in the third specific aim.

Broader Impact: The goal of this project is to develop a framework that provides a seamless integration of detailed chemistry and complex flow fields and is demonstrated by analyzing combustion processes. However, the successful completion of this work will have significant impact on the simulation and optimization of reactive systems in almost all industrial sectors including chemical, pharmaceutical and energy. Emphasis will be placed on the established collaboration with industrial partners, which will be further strengthened through students' summer internships for both graduate and undergraduate students. Dissemination of the results will be achieved through presentation in national and international meetings and journal publications. Both PIs have track records in research dissemination and educational activities. Students affiliated with the program SUPER (Science for Undergraduates a Program for Excellence in Research) of Douglass College of Women will be actively recruited for this project. Moreover with this project the PIs plan to illustrate a prototype for the application of their adaptive chemistry approach using the NSF TeraGrid that can be used by other researchers.