92nd NIA CFD Seminar Webcast: SLAU2 and Post Limiter for (Unlimited) Second-Order Flow Simulations on Unstructured Grids by Keiichi Kitamura

August 8, 2017 - Leave a Response

92nd NIA CFD Seminar

Topic: SLAU2 and Post Limiter for (Unlimited) Second-Order Flow Simulations on Unstructured Grids

Date: Friday, August 18, 2017

Time: 11:00am-noon (EST)

Room: NIA, Rm137

Speaker: Keiichi Kitamura

Speaker Bio: Dr. Keiichi Kitamura was an exchange student at University of Michigan, Ann Arbor (2007), and received Dr. of Engineering from Nagoya University, Japan (2008). Then he experienced Postdoctoral Researcher at JAXA (2008-2011) and NASA Glenn (2011-2012), Assistant Prof. at Nagoya University (2012-2014), and became Associate Prof. at Yokohama National University, Japan (2014). He has proposed several numerical flux functions such as SLAU2 (2013), and also a new limiting strategy called “Post Limiter” (2017) to turn off a slope limiter at unnecessary places.

Abstract: This talk will present two methods: SLAU2 flux function and “Post Limiter.” SLAU2 is robust against shockwave-induced anomalous solutions at hypersonic speeds (“carbuncle” phenomena), while it can be used at low speeds e.g., Mach 0.001 – thus, designated as an all-speed scheme. SLAU2, with its predecessor SLAU, has been incorporated into JAXA’s CFD code “FaSTAR”, and widely used by many researchers and practitioners in- and outside Japan. The present talk will focus on its very recent extension to supercritical fluids, in which an energy equation to be solved was replaced by its mathematically-equivalent, pressure-evolution equation, to suppress numerical oscillations.

“Post Limiter (simple a posteriori slope limiter)” is a means to deactivate a conventional slope limiter as much as possible (even at shocks), unless it is truly needed. In other words, “unlimited” slopes are favored rather than the limited ones by the slope limiter at all the cell-interfaces. As a result, dramatic improvements of both flow resolution (four times in each dimension) and convergence have been observed. This approach is powerful especially when a spatially second-order reconstruction is performed and grid points are clustered to physics-rich regions on unstructured grids, such as in FaSTAR.

Additional information, including the webcast link, can be found at the NIA CFD Seminar website:

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

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TODAY: 91st NIA CFD Seminar Webcast: Finite Element Domain Decomposition Algorithms & Software With Applications in Civil/Structural/Mechanical/Aerospace/Electro-Magnetic/Acoustics/Transportation Engineering by Duc T. Nguyen

August 1, 2017 - Leave a Response

91st NIA CFD Seminar

Topic: Finite Element Domain Decomposition Algorithms & Software With Applications in Civil/Structural/Mechanical/Aerospace/Electro-Magnetic/Acoustics/Transportation Engineering

Date: Tuesday, August 1, 2017

Time: 11:00am-noon (EST)

Room: NIA, Rm101

Speaker: Duc T. Nguyen

Speaker Bio: Dr. Duc T. Nguyen obtained his B.S. (Northeastern University, 1974), M.S. (U.C. Berkeley, 1976), and Ph.D. (University of Iowa, 1982) degrees in Civil/Structural Engineering. He has been a Structural Engineering faculty at Old Dominion University since 1985. His teaching activities and research in Large-Scale Parallel (Finite Element) Computational Mechanics, Equation & Eigen-Solvers, Sensitivity Analysis & Engineering Optimization, and in STEM Related Educational Topics have led to several international/national/regional awards.

Abstract: Serial and parallel computing methods for use in large-scale structural analysis, and other engineering/science applications (such as Computational Fluid Dynamics, Acoustics, Electro-magnetic, Transportation Engineering Modeling, Automotive Engineering, Mechanical/Aerospace/Civil/Electrical Engineering disciplines) are high-lighted.

The seminar speaker will briefly explain important numerical topics, such as parallel sparse/dense matrix operations, Domain Decomposition (DD) partitioned algorithms, mixed direct-iterative (linear) solvers with DD formulation, solution algorithms for solving systems of Simultaneous Linear Equations (SLE) where the system (stiffness) matrix can be symmetrical (or unsymmetrical), positive (or negative) definite, or indefinite, how to handle SLE with Multi-Point Constraints (MPC), efficient algorithms for solving system of non-linear equations, Sensitivity Analysis with DD formulation, Genetic and Differential Evolution (DE) Algorithms for size, shape and topology optimization.

Medium to large-scale, practical NASA finite element models [such as the High Speed Civil Transport (HSCT) Aircraft, space shuttle Solid Rocket Booster (SRB), NASA LaRC finite element acoustic 3-D model], Automobile Finite Element model, Shortest Paths in real-life Transportation Networks, size-shape-topology optimization for 2-D bridge structures, etc… will be presented to demonstrate the effectiveness of the developed numerical algorithms.

Additional information, including the webcast link, can be found at the NIA CFD Seminar website:

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

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