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Large-Eddy Simulation: Current Capabilities, Recommended Practices, and Future Research

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Large-Eddy Simulation: Current Capabilities, Recommended Practices, and Future Research NASA/TM—2009-215616 AIAA–2009–948 Large-Eddy Simulation: Current Capabilities, Recommended Practices, and Future Research Nicholas J. Georgiadis Glenn Research Center, Cleveland, Ohio Donald P. Rizzetta Air Force Research Laboratory, Wright-Patterson Air Force Base, Dayton, Ohio Christer Fureby FOI, Swedish Defense Research Agency, Stockholm, Sweden July 2009 NASA STI Program . in Profile Since its founding, NASA has been dedicated to the • CONFERENCE PUBLICATION. Collected advancement of aeronautics and space science. The papers from scientific and technical NASA Scientific and Technical Information (STI) conferences, symposia, seminars, or other program plays a key part in helping NASA maintain meetings sponsored or cosponsored by NASA. this important role. • SPECIAL PUBLICATION. Scientific, The NASA STI Program operates under the auspices technical, or historical information from of the Agency Chief Information Officer. It collects, NASA programs, projects, and missions, often organizes, provides for archiving, and disseminates concerned with subjects having substantial NASA’s STI. The NASA STI program provides access public interest. to the NASA Aeronautics and Space Database and its public interface, the NASA Technical Reports • TECHNICAL TRANSLATION. English- Server, thus providing one of the largest collections language translations of foreign scientific and of aeronautical and space science STI in the world. technical material pertinent to NASA’s mission. Results are published in both non-NASA channels and by NASA in the NASA STI Report Series, which Specialized services also include creating custom includes the following report types: thesauri, building customized databases, organizing and publishing research results. TECHNICAL PUBLICATION. Reports of completed research or a major significant phase For more information about the NASA STI of research that present the results of NASA program, see the following: programs and include extensive data or theoretical analysis. Includes compilations of significant • Access the NASA STI program home page at scientific and technical data and information http://www.sti.nasa.gov deemed to be of continuing reference value. NASA counterpart of peer-reviewed formal • E-mail your question via the Internet to help@ professional papers but has less stringent sti.nasa.gov limitations on manuscript length and extent of graphic presentations. • Fax your question to the NASA STI Help Desk at 443–757–5803 • TECHNICAL MEMORANDUM. Scientific and technical findings that are preliminary or • Telephone the NASA STI Help Desk at of specialized interest, e.g., quick release 443–757–5802 reports, working papers, and bibliographies that contain minimal annotation. Does not contain • Write to: extensive analysis. NASA Center for AeroSpace Information (CASI) 7115 Standard Drive • CONTRACTOR REPORT. Scientific and Hanover, MD 21076–1320 technical findings by NASA-sponsored contractors and grantees. NASA/TM—2009-215616 AIAA–2009–948 Large-Eddy Simulation: Current Capabilities, Recommended Practices, and Future Research Nicholas J. Georgiadis Glenn Research Center, Cleveland, Ohio Donald P. Rizzetta Air Force Research Laboratory, Wright-Patterson Air Force Base, Dayton, Ohio Christer Fureby FOI, Swedish Defense Research Agency, Stockholm, Sweden Prepared for the 47th Aerospace Sciences Meeting and sponsored by American Institute of Aeronautics and Astronautics Orlando, Florida, January 5–8, 2009 National Aeronautics and Space Administration Glenn Research Center Cleveland, Ohio 44135 July 2009 Acknowledgments The authors are grateful to members of the AIAA Fluid Dynamics Technical Committee Large Eddy Simulation (LES) Working Group who contributed to the development of this article, and in particular to J.R. DeBonis, B.R. Smith, G.A. Blaisdell, and F. Ladeinde. They also wish to acknowledge M.R. Visbal and P.E. Morgan for useful conversations on LES. This work was sponsored by the Fundamental Aeronautics Program at the NASA Glenn Research Center. Level of Review: This material has been technically reviewed by technical management. Available from NASA Center for Aerospace Information National Technical Information Service 7115 Standard Drive 5285 Port Royal Road Hanover, MD 21076–1320 SpringÞ eld, VA 22161 Available electronically at http://gltrs.grc.nasa.gov Large-Eddy Simulation: Current Capabilities, Recommended Practices, and Future Research Nicholas J. Georgiadis National Aeronautics and Space Administration Glenn Research Center Cleveland, Ohio 44135 Donald P. Rizzetta Air Force Research Laboratory Wright-Patterson Air Force Base Dayton, Ohio 45433 Christer Fureby FOI Swedish Defense Research Agency Stockholm, Sweden This paper presents the results of an activity by the Large Eddy Simulation (LES) Working Group of the AIAA Fluid Dynamics Technical Committee to (1) address the current capabilities of LES, (2) outline recommended practices and key considerations for using LES, and (3) identify future research needs to advance the capabilities and reliability of LES for analysis of turbulent flows. To address the current capabilities and future needs, a survey comprised of eleven questions was posed to LES Working Group members to assemble a broad range of perspectives on important topics related to LES. The responses to these survey questions are summarized with the intent not to be a comprehensive dictate on LES, but rather the perspective of one group on some important issues. A list of recommended practices is also provided, which does not treat all aspects of a LES, but provides guidance on some of the key areas that should be considered. I. Introduction Until recently, Reynolds-averaged Navier Stokes (RANS) methods were used almost exclusively for the computational fluid dynamics (CFD) analysis of turbulent flows for practical engineering problems. RANS- based techniques are on one end of the spectrum of turbulent calculation methods, in which all turbulent fluid dynamic effects are replaced by a turbulence model. On the other end of the spectrum, Direct Numerical Simulation (DNS) methods calculate the entire turbulent energy spectrum by resolving all turbulent mo- tions. Although this avoids the limitations associated with turbulence modeling, DNS methods will remain computationally impractical in the foreseeable future for all but the simplest configurations. Large-Eddy Simulation (LES) methods, which directly calculate the large-scale turbulent structures and reserve modeling only for the smallest scales, may offer the best prospects for improving the fidelity of turbulent flow simula- tions. A related approach is the group of hybrid RANS/LES methods, where RANS is used in regions where the turbulence is in equilibrium, such as in wall boundary layers, and LES is used where non-equilibrium occurs, typically away from walls. In recent years, LES has seen an increase in usage for flows, where previously RANS methods were typically applied, for the following reasons: (1) rapid increases in computing power, memory, and storage, (2) realization that RANS methods inherently cannot handle certain classes of complex turbulent flow problems such as massively separated flows, (3) the availability of LES and hybrid RANS/LES methods in production class CFD codes. With this increased use of LES by more CFD practitioners, questions have arisen concerning the proper usage of LES, the level of solution fidelity that can be expected, and areas of method development that are needed to improve the utility of the technique. NASA/TM—2009-215616 This paper will provide the results of an effort conducted by the Large Eddy Simulation (LES) Working Group of the AIAA Fluid Dynamics Technical Committee (FDTC) to assess the current status of LES, pro- vide recommendations for future work, and provide a list of recommended practices and key considerations. Within the definition of “LES” used here we include hybrid RANS/LES methods. While an attempt is made here to address broad topics in LES, it is impossible to address every important issue within the scope this document. Further, much of the document represents opinions of the authors and the LES Working Group that contributed to this effort. As a result, these suggestions are not intended to be a comprehensive dictate on LES, but rather the perspective of one group on some important issues in LES and how the field may move forward in the future. II. Current Capabilities of LES To address the current capabilities of LES and identify limitations that require more work, a survey was posed to participants of the LES Working Group. In this section, the survey questions posed to this group are described and a summary of the responses is provided. For some of the questions, a consensus was reached on particular topics related to LES, but for other questions, a broad range of opinions resulted. This indicates that for certain areas in LES, there is not enough knowledge or experience in place to determine the merits of certain approaches (e.g. subgrid modeling) and more work is needed. The intent of the survey was to draw responses from a group that are representative of the broader community already using or considering usage of LES-based methods for turbulent flow simulations. The participants in the survey are listed in Table 1 and comprise industry, government, and academic interests. It is suggested that the interested reader may also consider review articles such as the overviews of LES 1 3 4 6 7,8 provided by Moin and Kim, Lesieur and Metais,2 Pope , Boris , Boris
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