Conferences, Lectures, & Seminars
Events for August
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AME Seminar
Sun, Aug 11, 2019 @ 03:30 PM - 04:30 PM
Aerospace and Mechanical Engineering
Conferences, Lectures, & Seminars
Speaker: Eckart Meiburg, UC Santa Barbara
Talk Title: Settling of Cohesive Sediment: Particle resolved Simulations
Abstract: We develop a physical and computational model for performing fully coupled, grain resolving Direct Numerical Simulations of cohesive sediment, based on the Immersed Boundary Method. The model distributes the cohesive forces over a thin shell surrounding each particle, thereby allowing for the spatial and temporal resolution of the cohesive forces during particle to particle interactions.
We test and validate the cohesive force model for binary particle interactions in the Drafting-Kissing-Tumbling aka DKT configuration. Cohesive sediment grains can remain attached to each other during the tumbling phase following the initial collision, thereby giving rise to the formation of flocs. The DKT simulations demonstrate that cohesive particle pairs settle in a preferred orientation, with particles of very different sizes preferentially aligning themselves in the vertical direction, so that the smaller particle is drafted in the wake of the larger one. This preferred orientation of cohesive particle pairs is found to remain influential for much larger simulations of 1,261 polydisperse particles released from rest. These simulations reproduce several earlier experimental observations by other authors, such as the accelerated settling of sand and silt particles due to particle bonding, the stratification of cohesive sediment deposits, and the consolidation process of the deposit. This final phase also shows the build-up of cohesive and direct contact intergranular stresses. The simulations demonstrate that cohesive forces accelerate the overall settling process primarily because smaller grains attach to larger ones and settle in their wakes. An investigation of the energy budget shows that the work of the collision forces substantially modifies the relevant energy conversion processes.
Biography: Eckart Meiburg received his Ph.D. from the University of Karlsruhe. After a postdoc at Stanford, he became an assistant professor in applied mathematics at Brown. He then moved to USC as associate then full professor. He later moved to UC Santa Barbara.
His research interests are fluid dynamics and transport phenomena, primarily computational fluid dynamics. He uses highly resolved direct numerical simulations to investigate physical mechanisms governing the spatio temporal evolution of a wide variety of geophysical, porous media, and multiphase flow fields. Some of his current interests are gravity and turbidity currents, Hele-Shaw displacements, double diffusive phenomena in particle laden flows, and internal bores.
Meiburg has received a Presidential Young Investigator Award, a Humboldt Senior Research Award, and a Senior Gledden Fellowship Institute of Advanced Studies, University of Western Australia. He is fellow of the American Physical Society and the ASME, was the 2012 Lorenz G. Straub Award Keynote Speaker at Univ. Minn., gave the Ronald F. Probstein Lecture at MIT in 2018, and was Shimizu Visiting Professor at Stanford University.
Host: Bermejo-Moreno
Location: SLH 102
Audiences: Everyone Is Invited
Contact: Tessa Yao
This event is open to all eligible individuals. USC Viterbi operates all of its activities consistent with the University's Notice of Non-Discrimination. Eligibility is not determined based on race, sex, ethnicity, sexual orientation, or any other prohibited factor. -
AME Seminar
Wed, Aug 28, 2019 @ 03:30 PM - 04:30 PM
Aerospace and Mechanical Engineering
Conferences, Lectures, & Seminars
Speaker: Oscar Bruno, CalTech
Talk Title: Fast Spectral Time Domain PDE Solvers for Complex Structures: The Fourier Continuation Method
Abstract: We present fast spectral solvers for time-domain Partial Differential Equations. Based on a novel Fourier-Continuation (FC) method for the resolution of the Gibbs phenomenon, these methodologies give rise to time-domain solvers for PDEs for general engineering problems and structures. The methods enjoy a number of desirable properties, including spectral time evolution essentially free of pollution or dispersion errors for general PDEs in the time domain, with conditional unconditional stability for explicit alternating-direction methods and high order of temporal accuracy. A variety of applications to linear and nonlinear PDE problems will be presented, including the diffusion and wave equations, the Navier-Stokes equations and the elastic wave equation, demonstrating the significant improvements the new algorithms can provide over the accuracy and speed resulting from other approaches.
Biography: Oscar Bruno received his Ph.D. degree from the Courant Institute of Mathematical Sciences, New York University. Following graduation, he held a two-year position as Visiting Assistant Professor with the University of Minnesota, and he then joined the faculty of the Georgia Institute of Technology aka Georgia Tech, where he served as Assistant and Associate Professor. After a four-year period with Georgia Tech, in 1995 he joined the faculty of the California Institute of Technology aka Caltech, where he has served as Professor in the Department of Applied and Computational Mathematics since 1998, and as Executive Officer of that department during 1998-2000. Dr. Bruno has research interests that lie in areas of optics, elasticity and electromagnetism, remote sensing and radar, overall electromagnetic and elastic behavior of materials: solids, fluids, composites materials, multiplescale geometries, and phase transitions. Dr. Bruno has directed 37 graduate students and postdocs during his career, and his research efforts have resulted in the publication of more than 100 refereed articles, and have been acknowledged by his plenary presentations at many international conferences, his service on editorial boards of important scientific journals, including the SIAM Journal of Applied Mathematics, the SIAM Journal on Scientific Computing, and the Proceedings of the Royal Society of London, and his election to honorary societies, most notably the Council for the Society for Industrial and Applied Mathematics. Dr. Bruno is a recipient of the Sigma-Xi faculty award, the Friedrichs Award for an outstanding dissertation in mathematics, a Young Investigator Award from the National Science Foundation. and a Sloan Foundation Fellowship. Dr. Bruno is a SIAM Fellow in the class of 2013, and a National Security NSSEFF Vannevar Bush fellow, in the class of 2016.
Host: Pahlevan
Location: SLH 102
Audiences: Everyone Is Invited
Contact: Tessa Yao
This event is open to all eligible individuals. USC Viterbi operates all of its activities consistent with the University's Notice of Non-Discrimination. Eligibility is not determined based on race, sex, ethnicity, sexual orientation, or any other prohibited factor.
