53rd NIA CFD Seminar Webcast: Numerical Simulations of General Conservation Laws Using the Space-Time Conservative CESE Method by Chau-Lyan Chang

September 2, 2014 - Leave a Response

53rd NIA CFD Seminar

Topic: Numerical Simulations of General Conservation Laws Using the Space-Time Conservative CESE Method

Date: Tuesday, September 09, 2014

Time: 11:00am-noon (EDT)

Room: NIA, Rm137

Speaker: Chau-Lyan Chang

Speaker Bio: Dr. Chau-Lyan Chang is a research scientist from the Computational AeroSciences Branch at NASA Langley Research Center. His primary research interest is in unstructured mesh CFD methods and code development. He also works on numerical computations of boundary layer stability and transitions. He actively maintains LASTRAC software and interacts with users from academia and industry.

Abstract: Governing equations of most engineering disciplines can be written as general conservation laws by enforcing mass, momentum, and energy balances. Modern computational methods are devised to provide accurate solutions to these conservation laws in the discretized space. The space-time conservation element solution element (CESE) method introduced in 1990s is a numerical framework for general conservation laws designed to provide discretized solutions in the space-time domain with considerations to ensure accuracy and robustness. The CESE method is constructed based on a non-dissipative, space time inversion invariant core scheme. Numerical dissipations are added as required. Discretized equations for dependent variables and high derivatives are formulated by enforcing both local and global conservations. It can be shown that fundamental quantities such as mass, momentum, and energy are strictly conserved both in the local conservation elements as well as the entire computational domain. To handle solutions with discontinuities, the integration volumes have interfaces that only encompass the smooth regions where solution polynomials are valid. With these constructs, the CESE numerical framework is free of ad-hoc reconstructions of physical quantities associated with interfacial discontinuity or approximations of kinetic energy. This talk discusses the fundamental concepts and development of the CESE framework with primary focus on 3D Navier-Stokes computations. High fidelity simulations of problems with multiple temporal/spatial-scales and physics are tackled with time accurate local time-stepping and high-order frameworks for unstructured meshes. Applications of the CESE method in other disciplines outside of NASA will be briefly discussed.

Additional information, including the webcast link, can be found at the NIA CFD Seminar website, which is temporarily located at

http://www.hiroakinishikawa.com/niacfds/index.html

 
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TODAY: 52nd NIA CFD Seminar: Structural and Multidisciplinary Design Optimization of Aircraft with Next-Generation Lightweight Materials by Graeme Kennedy

August 27, 2014 - Leave a Response

52nd NIA CFD Seminar

Topic: Structural and Multidisciplinary Design Optimization of Aircraft with Next-Generation Lightweight Materials

Date: Wednesday, August 27, 2014

Time: 11:00am-noon (EDT)

Room: NIA, Rm101

Speaker: Graeme Kennedy

Speaker Bio: Dr. Graeme Kennedy is an Assistant Professor in the School of Aerospace Engineering at the Georgia Institute of Technology where he leads his research group focused on developing novel design optimization methods for structural and multidisciplinary aerospace systems. Before joining the Georgia Tech faculty, he worked as a Postdoctoral Research Fellow at the University of Michigan in the Multidisciplinary Design Optimization lab. He received his Ph.D. from the University of Toronto Institute for Aerospace Studies (UTIAS) under the supervision of Prof. Joaquim R.R.A. Martins in 2012 and hisM.A.Sc. from UTIAS under the supervision of Prof. Jorn Hansen in 2007. He received his undergraduate degree in Aerospace Engineering from the University of Toronto in 2005. A complete list of papers and ongoing projects is available on Dr. Kennedy’s website: http://gkennedy.gatech.edu/.

Abstract: The use of advanced lightweight structures has enabled significant performance improvements for the present generation of transport aircraft. New structural materials, manufacturing techniques and multi-functional structural technologies will lead to even greater improvements for future aircraft. These new technologies give engineers greater flexibility to tailor aircraft structures to meet stringent design requirements. However, the large design space associated with this flexibility can be difficult to navigate since there is a limited knowledge base to help guide design decisions. Advanced computational design methods that employ high-fidelity structural and multidisciplinary analysis are key tools to help engineers understand the complex trade-offs inherent in aircraft design, especially in the context of advanced structural technologies. In this seminar, I will present our work on structural and aerostructural optimization that begins to address these challenges. To meet the computational demands of high-fidelity simulation and design, we use gradient-based design optimization techniques in conjunction with parallel computational methods and efficient adjoint-based derivative evaluation. To illustrate our efforts in these areas, I will describe the development of our in-house parallel finite-element code designed for multidisciplinary analysis and gradient-based optimization of composite structures called the Toolkit for the Analysis of Composite Structures (TACS). To demonstrate the capabilities of our structural and aerostructural design optimization framework, I will present the results of a study comparing the design of metallic and composite wings for a large transport aircraft. These results will show the benefits of using an integrated, gradient-based aerostructural analysis and design optimization framework.

Additional information, including the webcast link, can be found at the NIA CFD Seminar website, which is temporarily located at

http://www.hiroakinishikawa.com/niacfds/index.html

 
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