National Science Foundation     |     Directorate for Engineering  (ENG)
Division of Chemical, Bioengineering, Environmental, & Transport Systems  (CBET)
CBET Award Achievements (Nuggets)
Notable Accomplishments from CBET Awards
Cyber-enabled Investigations of Turbulence Fine Scale Structure
Pui-Kuen Yeung    Georgia Institute of Technology

Background:  Turbulent flows are very challenging to predict and arise in many important practical problems.  The Yeung Group at Georgia Institute of Technology has studied turbulent mixing through very intensive numerical simulations using advanced cyberinfrastructure resources allocated at several TeraGrid supercomputer sites supported by NSF.  Recent simulations have benefited from advances in parallel algorithms achieved in collaboration with high-performance computing specialists at the San Diego Supercomputer Center (SDSC).

Results:  Through massively parallel simulations of turbulence on a periodic domain, with grid resolution up to 4096 x 4096 x 4096, the researchers have been able to examine the structure of turbulence over a wide range of scale sizes, and with greater precision than possible before.  A strong emphasis is on implications of the fine-scale structure for important problems of turbulent mixing and dispersion.

P.K. Yeung Image
Figures.  Cyber-enabled Investigations of Turbulence Fine Scale Structure.  The figure on the left is a sample visualization of local flow properties in turbulent flow in a spatially periodic computational domain with 2048 grid points in each direction.  The figure on the right is a zoom-in showing the complex details in greater clarity.  Two quantities are being visualized: namely fluctuations of the enstrophy (red iso-contours) and energy dissipation rate (blue volume rendering) which represent, respectively, the intensity of local deformation and rotation in the flow.  Both quantities have important roles in problems such as combustion and pollutant dispersion.  Intense enstrophy typically resides in long, thin tubes (called worms) surrounded by large energy dissipation (which is more diffuse).  This information can be used to develop models which relate the details of turbulent mixing to the local structure of the flow.  High-performance computing techniques are required to reach sufficiently high Reynolds number where extreme events in dissipation and enstrophy fluctuations become increasingly important.
Image Credit:  Diego Donzis, Texas A&M University; Kelly Gaither and Greg Johnson of Texas Advanced Computing Center (TACC)

This project addresses the NSF Strategic Outcome Goals, as described in the NSF Strategic Plan 2006-2011, as follows:
Primary Strategic Outcome Goal:      (1) Discovery:  The work of the Yeung Group is consistent with NSF's mission of fostering research that will advance the frontiers of knowledge, at the level of global leadership in fundamental and transformational science and engineering.  Numerical simulations of turbulent mixing and dispersion in this work are the largest in the world, and at the highest Reynolds number and/or Schmidt number when compared with related work in the international research community.
                                                                   (1) Discovery Category:
                                                                          - Engineering Research
Secondary Strategic Outcome Goal:  (2) Research Infrastructure:  The researchers have created a very large numerical simulation database that is helpful for testing theories of local turbulence structure and for developing new models for predicting mixing and dispersion.  The numerical simulation tool will enable scientists to study important effects of turbulent flow at even greater grid resolution in the future as well as lead to advances in state-of-the-art computational science towards the Petascale.
                                                                   (2) Research Infrastructure Category:
                                                                          - Other Infrastructure and Research Resources
Secondary Strategic Outcome Goal:  (3) Learning:  Over the years this project has provided partial support to three PhD students.  One of these has, after a period of postdoctoral training with a co-funded collaborator while remaining involved in the research, been appointed as assistant professor at a major research university.
                                                                   (3) Learning Categories:
                                                                          - Graduate Education and Graduate Student Research
                                                                          - Postdoctoral Education
                                                                          - Broadening participation to Improve Workforce Development

In terms of Intellectual Merit, this research has notable outcomes because these simulations are capturing and resolving accurately a wider range of scales than available in past simulations or even some laboratory experiments.  As a result the simulations are conducted in flow conditions that relate increasingly close, in essence, to flow conditions that characterize turbulent mixing in practical applications.  This research is leading to more robust understanding of difficult issues that could not be addressed conclusively before.

In terms of Broader Impacts, this outcome is notable.  This cyber tool can simulate turbulence in unprecedented detail and help provide impetus for state-of-the-art high-performance computing.

This research is Transformative.  Through the aid of supercomputing infrastructure, the researchers have created a very large numerical simulation database.  This simulation database captures the details of local straining and rotation in ways not otherwise achievable.  This tool could transform the way combustion and pollutant dispersion are modeled since these crucial processes can now be simulated in great detail.

This research represents Broadening Participation.  The Principal Investigator (PI) is hearing impaired.  A co-PI (K.R. Sreenivasan) received the Nicholson Medal for Human Outreach at the American Physical Society March 2009 Meeting in Pittsburgh.  Finally, the PIs work has also been featured in the 2008 TeraGrid Science Highlights publication, with an advanced visualization image created by experts at the Texas Advanced Computing Center.

Existing or potential Societal Benefits of this research:  Unsatisfactory understanding of turbulence, within the research community, continues to be a vexing problem for important areas such as transportation, pollution dispersion, and effective energy conversion.  The PI is addressing the core of this problem by determining how turbulent properties at different length scales interact using one of the most computationally intensive studies of any type to date.

Program Director:
William Schultz
CBET Program Director - Fluid Dynamics
NSF Award Number:   0553867
Award Title:
  Collaborative Research: Large Numerical Simulations of Turbulence and Reynolds, Schmidt and Rossby Number Scalings
PI Name:   Pui-Kuen Yeung
Institution Name:   Georgia Institute of Technology
Program Element Codes:   7641, 7454, 7446, 7298, 1443
NSF Investments:
  - American Competitiveness Initiative (ACI)
- Cyberinfrastructure
CBET Nugget:

  FY 2009

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This Nugget was Updated on 31 August 2009.