About

Robert C. Armstrong is the Chevron Professor in Chemical Engineering at MIT and is a Post-Tenure faculty member. His role involves leading research and education in the field of chemical engineering, with a focus on advancing knowledge and innovation within the discipline. As a faculty member, he contributes to the department's mission of excellence in research, teaching, and community engagement, supporting the development of future engineers and scientists.

Research topics

• Mechanics
• Materials science
• Physics
• Classical mechanics
• Mathematics

Selected publications

• Time-rate-transformation framework for targeted assembly of short-range attractive colloidal suspensions

  Materials Today Advances · 2020-01-13 · 1 citations

  preprintOpen access

  The aggregation of attractive colloids has been extensively studied from both theoretical and experimental perspectives as the fraction of solid particles is changed, and the range, type, and strength of attractive or repulsive forces between particles varies. The resulting gels, consisting of disordered assemblies of attractive colloidal particles, have also been investigated with regards to percolation, phase separation, and the mechanical characteristics of the resulting fractal networks. Despite tremendous progress in our understanding of the gelation process, and the exploration of different routes for arresting the dynamics of attractive colloids, the complex interplay between convective transport processes and many-body effects in such systems has limited our ability to drive the system toward a specific configuration. Here, we study a model attractive colloidal system over a wide range of particle characteristics and flow conditions undergoing aggregation far from equilibrium. The complex multiscale dynamics of the system can be understood using a time-rate-transformation diagram adapted from understanding of materials processing in block copolymers, supercooled liquids, and much stiffer glassy metals to direct targeted assembly of attractive colloidal particles.

  PublisherOA PDFDOI

• Multiscale Nature of Thixotropy and Rheological Hysteresis in Attractive Colloidal Suspensions under Shear

  Physical Review Letters · 2019-12-10 · 45 citations

  articleOpen access

  Colloids with short range attractions self-assemble into sample-spanning structures, whose dynamic nature results in a thermokinematic memory of the deformation history, also referred to as "thixotropy." Here, we study the origins of the thixotropic effect in these time- and rate-dependent materials by investigating hysteresis across different length scales: from particle-level local measurements of coordination number (microscale), to the appearance of density and velocity fluctuations (mesoscale), and up to the shear stress response to an imposed deformation (macroscale). The characteristic time constants at each scale become progressively shorter, and hysteretic effects become more significant as we increase the strength of the interparticle attraction. There are also strong correlations between the thixotropic effects we observe at each scale.

  PublisherOA PDFDOI

• Plausible Energy Futures: A Framework for Evaluating Options, Impacts, and National Energy Choices.

  DSpace@MIT (Massachusetts Institute of Technology) · 2019-10-30

  articleOpen accessSenior author

  The global energy system is undergoing major transformations. The world faces a dual challenge of meeting increasing energy demand while reducing greenhouse gas emissions. This change is characterized by the convergence of power, transportation, industrial, and building sectors, and the surge of multi-sectoral integration. Such transformation of energy systems requires a combination of technology selection and policy choices to ensure providing reliable and clean energy. Understanding the implications of these dynamics is challenging and requires a holistic approach to provide systems level insights. In this working paper, we provide an overview of energy transformation analysis and projection tools and discuss the use of quantitative methods to examine possible future energy pathways. This is done to facilitate achieving decarbonization goals by providing thought leaders and policy makers with a robust framework in which energy choices and decarbonization goals can be made based on lifecycle analyses. We synthetize our findings applicable to modeling tools based on discussions with colleagues in other academic institutions and government labs and provide a summary of a wide range of lifecycle assessment (LCA) and energy modeling tools. Our assessment shows that although there is considerable related research work emerging, there is a lack of readily available or generally accepted quantitative models and tools that consider a broad and robust lifecycle analysis approach for a range of plausible energy futures at regional and national levels. Such a tool is needed to help policy makers, industry, investors, and the financial sector to better understand and make decisions on energy choices and energy transitions, and avoid narrowly framed and advocacy-driven pathways. We at MIT have substantial experience in building and maintaining energy system assessment tools: i) A comprehensive system-level and pathway-level lifecycle assessment model, which is called the Sustainable Energy Systems Analysis Modeling Environment (SESAME). SESAME is a publicly available, open access model with multi-sector representation. ii) The Integrated Global System Modeling framework (IGSM), which combines an economy-wide, multi-sector, multi-region computable general equilibrium (CGE) model (The MIT Economic Projection and Policy Analysis model, EPPA) with a natural systems component (The MIT Earth System model, MESM). The IGSM is an integrated assessment model (IAM). To quantify additional environmental impact categories such as air pollutants and water footprint, we develop an expanded SESAME platform. For an economy-wide scenario analysis, we use the MITEI Energy Choice Program Working Paper 3 modeling results from our EPPA model. The expanded SESAME version will be a publicly available technology options and scenario analysis tool that can use input information from any economy-wide system (or use the default settings that represent our base-case values). The tool will evaluate options, impacts, and national energy choices for exploring the impacts of relevant technological, operational, temporal, and geospatial characteristics of the evolving energy system. It focuses on lifecycle analysis with high technology resolution (linked with the existing MIT energy-economic models) that provides economic information and quantifies lifecycle GHG emissions, as well as impacts related to criteria pollutants and water. Such analysis highlights how effective policy choices and technology selection can reduce such environmental impacts

  Publisher

• Time-Rate-Transformation framework for targeted assembly of short-range\n attractive colloidal suspensions

  arXiv (Cornell University) · 2019-11-06

  preprintOpen access

  The aggregation of attractive colloids has been extensively studied from both\ntheoretical and experimental perspectives as the fraction of solid particles is\nchanged, and the range, type and strength of attractive or repulsive forces\nbetween particles varies. The resulting gels consisting of disordered\nassemblies of attractive colloidal particles, have also been investigated with\nregards to percolation, phase separation, and the mechanical characteristics of\nthe resulting fractal networks. Despite tremendous progress in our\nunderstanding of the gelation process, and the exploration of different routes\nfor arresting the dynamics of attractive colloids, the complex interplay\nbetween convective transport processes and many-body effects in such systems\nhas limited our ability to drive the system towards a specific configuration.\nHere we study a model attractive colloidal system over a wide range of particle\ncharacteristics and flow conditions undergoing aggregation far from\nequilibrium. The complex multiscale dynamics of the system can be understood\nusing a Time-Rate-Transformation diagram adapted from understanding of\nmaterials processing in block copolymers, supercooled liquids and much stiffer\nglassy metals to direct targeted assembly of attractive colloidal particles.\n

  PublisherOA PDFDOI

• Invited Papers on Transport Phenomena in Celebration of Professor Robert Byron Bird’s 95th Birthday

  Physics of Fluids · 2019-02-01

  articleOpen access1st authorCorresponding

  First Page

  PublisherOA PDFDOI

• Microstructural Rearrangements and their Rheological Implications in a Model Thixotropic Elastoviscoplastic Fluid

  Physical Review Letters · 2017-01-27 · 78 citations

  articleOpen accessSenior author

  We identify the sequence of microstructural changes that characterize the evolution of an attractive particulate gel under flow and discuss their implications on macroscopic rheology. Dissipative particle dynamics is used to monitor shear-driven evolution of a fabric tensor constructed from the ensemble spatial configuration of individual attractive constituents within the gel. By decomposing this tensor into isotropic and nonisotropic components we show that the average coordination number correlates directly with the flow curve of the shear stress versus shear rate, consistent with theoretical predictions for attractive systems. We show that the evolution in nonisotropic local particle rearrangements are primarily responsible for stress overshoots (strain-hardening) at the inception of steady shear flow and also lead, at larger times and longer scales, to microstructural localization phenomena such as shear banding flow-induced structure formation in the vorticity direction.

  PublisherOA PDFDOI

• The frontiers of energy

  Nature Energy · 2016-01-11 · 323 citations

  articleOpen access1st authorCorresponding
  PublisherOA PDFDOI

• A Customizable, Scalable Scheduling and Reporting System

  Simulation in Healthcare The Journal of the Society for Simulation in Healthcare · 2014-03-10 · 1 citations

  article

  INTRODUCTION: Scheduling is essential for running a facility smoothly and for summarizing activities in use reports. The Penn State Hershey Clinical Simulation Center has developed a scheduling interface that uses off-the-shelf components, with customizations that adapt to each institution's data collection and reporting needs. METHODS: The system is designed using programs within the Microsoft Office 2010 suite. Outlook provides the scheduling component, while the reporting is performed using Access or Excel. An account with a calendar is created for the main schedule, with separate resource accounts created for each room within the center. The Outlook appointment form's 2 default tabs are used, in addition to a customized third tab. The data are then copied from the calendar into either a database table or a spreadsheet, where the reports are generated.Incorporating this system into an institution-wide structure allows integration of personnel lists and potentially enables all users to check the schedule from their desktop. Outlook also has a Web-based application for viewing the basic schedule from outside the institution, although customized data cannot be accessed. RESULTS: The scheduling and reporting functions have been used for a year at the Penn State Hershey Clinical Simulation Center. The schedule has increased workflow efficiency, improved the quality of recorded information, and provided more accurate reporting. CONCLUSIONS: The Penn State Hershey Clinical Simulation Center's scheduling and reporting system can be adapted easily to most simulation centers and can expand and change to meet future growth with little or no expense to the center.

  PublisherDOI

• R. Byron Bird: The integration of transport phenomena into chemical engineering

  AIChE Journal · 2014-01-03 · 5 citations

  article1st authorCorresponding

  This article, as is this issue of the AIChE Journal , is a tribute to R. Byron Bird, who has had a profound impact on the discipline of chemical engineering, playing a dominant role in the chemical engineering science paradigm shift that occurred around 1960. His textbook, Transport Phenomena , with Warren Stewart and Edwin Lightfoot, fundamentally changed the way chemical engineers are taught fluid mechanics, heat transfer, and mass transfer. By showing the interconnections among molecular, microscopic, and macroscopic treatments of these three transport processes, as well as the underlying similarities among the three transport processes, he has enabled chemical engineers to contribute to many new areas. In his research he has focused on polymeric fluids – their rheology and fluid mechanics – again spanning molecular to macroscopic problems. Bird is also known throughout the profession as a superb teacher and lecturer. He is gifted in languages and music, and he has a great love of the outdoors. In this article, I try to highlight some of Bird's history and accomplishments in these many areas. His influence is clear in the papers that follow. © 2014 American Institute of Chemical Engineers AIChE J , 60: 1219–1224, 2014

  PublisherDOI

• Systems analysis of hybrid, multi-scale complex flow simulations using Newton-GMRES

  Rheologica Acta · 2012-07-19 · 4 citations

  articleSenior author
  PublisherDOI

Frequent coauthors

• Robert A. Brown

  61 shared

• Gareth H. McKinley

  12 shared

• R. Byron Bird

  7 shared

• Ole Hassager

  Technical University of Denmark

  7 shared

• Todd Salamon

  Nokia (United States)

  6 shared

• Gregory C. Rutledge

  6 shared

• Antony N. Beris

  University of Delaware

  5 shared

• David E. Bornside

  5 shared

Education

• Ph.D., Chemical Engineering

  Massachusetts Institute of Technology

  1985

• M.S., Chemical Engineering

  Massachusetts Institute of Technology

  1980

• B.S., Chemical Engineering

  University of California, Berkeley

  1979

Awards & honors

• AIChE Founders Award for Outstanding Contributions to the Fi…
• Elected to the American Academy of Arts and Sciences, 2020
• Elected Member of the National Academy of Engineering, 2008
• Bingham Medal Award, 2006
• University of Wisconsin Distinguished Service Citation, 2001