NHERI SimCenter Webinar – Early Career Researcher Forum: Wednesday, February 21, 2018, 12 - 1pm (PST)

[announce at designsafe-ci.org]

​
*WEBINAR: Tsunami-Induced Turbulent Coherent Structures: Large-Scale
Experimental Observations and Interpretation*

*PRESENTER:*
Nikos Kalligeris is a Postdoctoral scholar in Civil Engineering at
University of California, Los Angeles. He received a BEng in Civil
Engineering from University of Brighton (UK), an MSc in Earthquake
Engineering from Imperial College (UK), an MSc in Environmental Engineering
from the Technical University of Crete (Greece), and a PhD in Civil
Engineering from the University of Southern California. His primary
research interests lie in nearshore hydrodynamics during extreme events,
such as tsunamis and hurricanes. His analysis uses numerical modeling,
well-controlled laboratory experiments and field observations. Dr
Kalligeris has been a member of several reconnaissance field surveys for
tsunamis around the world. Outside academia, he has worked as a part-time
professional civil engineer in Greece and has worked on numerous occasions
as a private consultant for international engineering firms in projects
related to tsunami and storm hazard assessment for nuclear and LNG
facilities.

*REGISTER for this webinar at:*
https://www.designsafe-ci.org/learning-center/training/simce
nter/webinar-180221/

Connection information will be distributed upon receipt of registration.

*ABSTRACT:*
Numerous historical accounts describe the formation of "whirpools" inside
ports and harbors during tsunami events, causing port operation
disruptions. Videos from the Japan 2011 tsunami revealed complex nearshore
flow patterns, resulting from the interaction of tsunami-induced currents
with the man-made coastline, and the generation of large eddies (or
turbulent coherent structures) in numerous ports and harbors near the
earthquake epicenter. In one video taken in the port of Oarai, a gigantic
eddy that occupies a big part of the port basin can be seen spinning for
tens of minutes, trapping ships inside the rotational flow, until it was
washed out by the next incoming wave.

To better understand how these tsunami-induced turbulent coherent
structures (TCS) are generated and how they evolve with time, we set-up an
experiment in a well-controlled environment using realistic scaling. A
physical configuration was created in the image of a port entrance at a
scale of ~1:27, and a small-amplitude, long-period wave creates a transient
flow through an asymmetric harbor channel. Separated region forms, which
coupled with the transient flow, lead to the formation of a stable
monopolar TCS. The surface flow is examined through mono- and stereo-PTV
techniques to extract surface velocity vectors. Surface velocity maps and
vortex flow profiles are used to study the experimental TCS generation and
evolution, and finally characterize the TCS flow structure. First-order
analytical tools are used to describe the TCS growth rate and kinetic
energy decay. This analysis provides the predictive tools to infer
time-scales of TCS development in shallow water flows, to first order. The
experimental set-up, analysis and results of this work are presented here.
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