
NSF Org: |
OAC Office of Advanced Cyberinfrastructure (OAC) |
Recipient: |
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Initial Amendment Date: | February 22, 2011 |
Latest Amendment Date: | February 27, 2015 |
Award Number: | 1054591 |
Award Instrument: | Standard Grant |
Program Manager: |
Sushil K Prasad
OAC Office of Advanced Cyberinfrastructure (OAC) CSE Directorate for Computer and Information Science and Engineering |
Start Date: | March 1, 2011 |
End Date: | February 28, 2018 (Estimated) |
Total Intended Award Amount: | $549,979.00 |
Total Awarded Amount to Date: | $662,629.00 |
Funds Obligated to Date: |
FY 2012 = $60,000.00 FY 2013 = $16,200.00 FY 2015 = $16,200.00 |
History of Investigator: |
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Recipient Sponsored Research Office: |
4333 BROOKLYN AVE NE SEATTLE WA US 98195-1016 (206)543-4043 |
Sponsor Congressional District: |
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Primary Place of Performance: |
4333 BROOKLYN AVE NE SEATTLE WA US 98195-1016 |
Primary Place of
Performance Congressional District: |
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Unique Entity Identifier (UEI): |
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Parent UEI: |
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NSF Program(s): |
CAREER: FACULTY EARLY CAR DEV, PMP-Particul&MultiphaseProcess, FD-Fluid Dynamics |
Primary Program Source: |
01001213DB NSF RESEARCH & RELATED ACTIVIT 01001314DB NSF RESEARCH & RELATED ACTIVIT 01001516DB NSF RESEARCH & RELATED ACTIVIT |
Program Reference Code(s): |
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Program Element Code(s): |
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Award Agency Code: | 4900 |
Fund Agency Code: | 4900 |
Assistance Listing Number(s): | 47.070 |
ABSTRACT
The combustion processes in electric power plants, jet engines, gasoline and diesel powered vehicles are the primary sources of the carbon dioxide emissions that grew by about 80% between 1970 and 2004. In the next decades, anthropogenic warming, due mostly to these CO2 emissions, could lead to impacts that are abrupt and irreversible, including increased water stress for hundreds of millions of people, ocean acidification, ecosystems change, and flooding (IPCC, 2007 & 2009). One method to help stabilize, and hopefully reverse, anthropogenic CO2 emissions is to reduce fossil fuel consumption by improving combustion efficiency. To do so, we must better understand the complex physical processes involved in spray combustion of liquid fuels. The vaporization rate of fuel droplets is recognized as a key mechanism in fuel-droplet combustion and most spray combustion devices operate in the turbulent regime. The effects of droplet vaporization on the dynamics of turbulence are therefore important, and the underlying physical mechanisms are largely unknown.
The main scientific objective of this research is to explain the physical mechanisms occurring in evaporating droplet-laden turbulence. The research is focused on explaining the effects of droplet/turbulence and droplet/droplet/turbulence interactions. The study is conducted by developing a petascale DNS code to simulate evaporating droplets in homogeneous turbulence. The novelty of the computational methodology stands in the ability to capture the process of heat, momentum and mass transfer of the liquid droplets with the surrounding fluid, while fully resolving the turbulent flow. The research is transformational to the science by performing unprecedented fully-resolved DNS of homogeneous turbulence (with an inertial-range of turbulence scales) laden with millions of vaporizing droplets using the NSF petascale supercomputer, Blue Waters (NCSA).
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
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PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
The 5th Assessment Report of the Intergovernmental Panel on Climate Change [Climate Change 2013: The Physical Science Basis] reads: “Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, sea level has risen, and the concentrations of greenhouse gases have increased”. “The atmospheric concentrations of carbon dioxide, methane, and nitrous oxide have increased to levels unprecedented in at least the last 800,000 years. Carbon dioxide concentrations have increased by 40% since pre-industrial times, primarily from fossil fuel emissions and secondarily from net land use change emissions. The ocean has absorbed about 30% of the emitted anthropogenic carbon dioxide, causing ocean acidification”. “Total radiative forcing is positive, and has led to an uptake of energy by the climate system. The largest contribution to total radiative forcing is caused by the increase in the atmospheric concentration of CO2 since 1750”.
One method to help stabilize, and hopefully reverse, anthropogenic CO2 emissions is to reduce fossil fuel consumption by improving combustion efficiency. To do so, we must better understand the complex physical and chemical processes involved in spray combustion of liquid fuels. The vaporization rate of fuel droplets is recognized as a key mechanism in fuel-droplet combustion and most spray combustion devices operate in the turbulent regime. The effects of droplets and their vaporization rate on the dynamics of turbulence are therefore important, and the underlying physical mechanisms are largely unknown. This NSF CAREER research has been aimed to advance the state-of-the-art in simulating droplet-laden turbulent flows and our understanding of the physical mechanisms occurring in such flows.
Intellectual Merit
We have developed new numerical methods for simulating droplet-laden flows with and without phase change (vaporization/condensation). These methods are tens of times faster than previous methods while being highly accurate and matching theoretical and experimental results (Dodd & Ferrante, Journal of Computational Physics 2014). With the use of supercomputers, we have performed fully-resolved direct numerical simulations of droplet-laden isotropic turbulence and explained the physical mechanisms of droplet/turbulence interaction. For example, we have, for the first time, explained the pathways of turbulence kinetic energy and the role of droplet surface tension in such dynamics (see Figures 1 and 2, Dodd & Ferrante, Journal of Fluid Mechanics 2016). Also, for the evaporating droplets, we have developed a computational methodology that is able to capture, for the first time, the process of heat, momentum and mass transfer of the liquid droplets with the surrounding fluid, while fully resolving the turbulent flow around the freely-moving, deforming and evaporating droplets, as well the flow inside the droplets (see Figure 3). The numerical results of the vaporization rate of droplets in turbulence match experimental results. Thus, we have advanced the state-of-the-art for simulating two-phase flows and the knowledge of the physics of droplet-laden turbulent flows. Furthermore, we have also developed a solver of fluid flows and of the 3D Poisson equation for petascale supercomputers, i.e. with hundreds of thousands computing cores. Such solver is tens of times faster than previously developed methods and will allow finer simulations and deeper understanding of turbulence.
Some of the contributions in which this research has advanced this field of research are discussed in the reviews of Professor Maxey "Droplets in turbulence: a new perspective" in Focus on Fluids of J. Fluid Mechanics 2016, and by Professor Elghobashi “Direct Numerical Simulation of Turbulent Flows Laden with Droplets or Bubbles” in the Annual Review of Fluid Mechanics 2019.
Broader Impacts
By explaining the physical mechanisms in droplet-laden isotropic turbulence, this CAREER research has opened the road to provide the required knowledge for developing models that may serve the combustion community and improve the efficiency of combustion of liquid fuels. The results of this research have been published in top journals of fluid mechanics and computational physics, have been presented at major national and international conferences in fluid mechanics, as well, at invited talks in Universities, such as Stanford University and Caltech.
We have developed fluid dynamic videos of droplet-laden flows that were presented at the Gallery of Fluid Motion of the American Physical Society:
- Interaction of Taylor lengthscale size droplets and isotropic turbulence
- Droplet Evaporation in a Turbulent Flow
The educational program has trained one Ph.D. student, who has graduated and continued his career as Postdoc at Stanford University, several undergraduate students, who have continued their careers as graduate students in top University, and, has also included women and under-represented minorities in engineering, for example, from the Pacific North West LSAMP program.
This CAREER has also enhanced infrastructure for research and education by establishing collaborations with the National Center for Supercomputing Applications (NCSA), and by developing partnership with international academic institutions such as the University of Manitoba, Canada.
Last Modified: 09/19/2018
Modified by: Antonino Ferrante
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