CAM Colloquium, 2017-01-27 - Peter Diamessis: Fast Discontinuous Element-Based Pressure Solvers and Keeping Things Non-Divergent: Remembering Sumedh Joshi as an Applied Mathematician and Human Being
From E. Cornelius on June 26th, 2017
Abstract: Sumedh Joshi was a brilliant and very promising young Applied Mathematician and wonderful person who, unfortunately, passed away suddenly and too soon in late August 2016, 3 months after receiving his Ph.D. from Cornell C.A.M. . In this presentation, as Sumedh’s friend and former thesis advisor, I will attempt to tell a story on his thesis work and my experience of him as a human being. The primary motivation for his research was the simulation of the propagation and destabilization into turbulence of internal solitary waves in stratified waters in long domains with variable bathymetry typical of the coastal ocean and lakes. The computational foundation of his research are discontinuous higher-order-element based techniques for the solution of the incompressible Navier-Stokes equations. The first part of my talk will present the essential components of a novel Schur-complement-based algorithm built by Sumedh to solve the highly challenging pressure Poisson equation in a highly efficient fashion, based on a two-level deflation-driven preconditioner. The second part of the talk will discuss a brilliantly-conceived singular-value-decomposition-based postprocessing technique for the associated pressure projection operator. Anybody who has known Sumedh would be well aware that he would love to have the scientific narrative of such a presentation regularly interrupted with random stories of any kind. I will attempt to do exactly that by offering snippets on his lovably sarcastic sense of humor, his thoughtful views on the human condition and his obsession with music, running, sports and basketball in particular.
Biography: Peter Diamessis received his B.S. from the National Tech. Univ. of Athens, Greece in 1995 and his Ph.D. from U.C. San Diego (with a specialization in fluid mechanics) in 2001. Following 4.5 years as a postdoc at U.S.C. he joined the faculty at Cornell’s School of Civil & Env. Eng. in 2006 where he became an Associate Professor in late 2011. His research interests operate along two axes: a) computational methods: the development of fast high-order discontinuous element based numerical methods for the incompressible Navier-Stokes equations and the associated numerical linear algebra and challenges of implementation from a high performance computing perspective and b) stratified flow physics: the study of stratified turbulent wakes, nonlinear effects in internal waves and instability/turbulence/resuspension in the interior and under internal/surface solitary waves. Infected by the basketball virus at a young age, he remains a die-hard fan of the Greek National basketball team and hopes for a rebirth under the guidance of Yiannis Antentokumpo, aka “The Greek Freak”. He and Sumedh engaged in endless conversations on the wondrous skills and potential of Yiannis and the current state of NBA basketball.