报告题目：A typical late-time singular regimes accurately diagnosed in stagnation-point-type helical solutions of 3D Euler flows    

    报告人：Dr. Miguel D Bustamante,

                        University College Dublin, Ireland

    时间：2017年3月23日(周四) 15:00-16:00

    地点：中科院力学所会议中心(5号楼)202会议室

    报告摘要：
        We revisit numerically and analytically the finite-time blowup of an infinite-energy helical solution of 3D Euler equations [Gibbon et al. (1999)]. By employing the method of mapping to regular systems [Bustamante (2011), Mulungye et al. (2015)], we establish a curious property of this solution that was not observed previously: near singularity time T*, a fast transient is followed by a slower late-time blowup regime that is well resolved spectrally at mid-resolutions (512^2), with a Gaussian wavenumber spectrum. The analyticity-strip width decays "slowly" to zero at t = T*, remaining above the collocation-point scale for all simulation times t < T* - 10^(-9000). Reaching such a proximity to singularity time is not possible in the original temporal variable, because of the floating-point double-precision barrier (10^(-16)). Due to this limitation on the original variables, the mapped variables now provide an improved assessment of the relevant blowup quantities, crucially with acceptable accuracy at an unprecedented closeness to singularity time: T*- t = 10^(-140).

    报告人简介：
    Dr. Miguel Bustamante is an Associate Professor in the School of Mathematics and Statistics at University College Dublin. He holds a bachelor’s degree and a PhD degree in Physics from Universidad de Chile. Before joining University College Dublin in 2009, he worked as a postdoctoral research fellow at LPS-Ecole Normale Superieure (2004-2006) in Paris, and a postdoctoral at University of Warwick (2006-2009). His current research interests lie in turbulence, extreme events and finite-time singularities in fluids and general nonlinear systems. He is also interested in the nonlinear energy-transfer mechanisms in wave systems such as precession resonance and dynamical systems approach. More information can be found from his website: http://miguel-d-bustamante.wixsite.com/maths