08-18-2017 | Keiichi Kitamura: SLAU2 and Post Limiter for (Unlimited) Second-Order Flow Simulations on Unstructured Grids

92nd NIA CFD Seminar: 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

Link: http://nia-mediasite.nianet.org/NIAMediasite100/Play/a6cd54189a044b208fc7224c3aae51ea1d?catalog=fe540232-73ef-4460-8462-0d8a1a25ea58

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.

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.