Large Scale Direct Numerical Simulations of Rogue Waves and Their Statistical Properties

When:  Mar 14, 2018 from 6:00 PM to 9:00 PM (PT)
Associated with  Northern California Section

University of California, Berkeley

Quichen Liu, Ph.D Student


TOPIC:
Rogue waves or freak waves are very large amplitude waves compared to the ambient waves in a given sea state. There are very few recording of such waves and therefore, despite years of research, very little is known about their properties. Here, we show through a statistical analysis that rogue waves in broadband non-breaking seas are spatially asymmetric for most realistic oceanic conditions. In addition to the top-down asymmetry due to nonlinear effects, we show that the two troughs adjacent to the rogue wave crest are generally of different depths, which is unlike the conventional picture of rogue waves with symmetric fore and aft troughs often obtained from model equations. The rogue-wave trough asymmetry is demonstrated for sea states 4 to 6 on Douglas Sea Scale. Considering the deepest trough leads to approximately 10% increase in the calculation of the mean rogue-wave height compared to previous results for rogue waves reported with symmetric troughs. This implies that estimates of rogue-wave trough-crest amplitudes based on model equations should be re-assessed upward for most realistic oceanic conditions. Furthermore, the upcoming rogue wave events can be inferred from spatial energy concentration. We use a statistical approach, and by investigating hundreds of numerical rogue wave realizations in weakly nonlinear wave fields establish a quantitative metric via which predictions can be made. The presented metric may establish a readily achievable measure to identify turbulent locations within a sea, through which timely preventive measures can be taken to minimize damages to lives and properties.


SPEAKER:
Qiuchen Guo received her BS degree (2012) in naval architecture and marine engineering from Tianjin University, China and joined the ocean engineering program at University of California, Berkeley, where she obtained her MS degree (2014). Now she is continuing her Ph.D. research on extreme ocean waves with Prof. M.-Reza Alam.

WEBINAR:
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Location

The Faculty Club at UC Berkeley
Minor Lane
Berkeley, CA 94720

Pricing Information

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Member $40.00
Non-member $45.00

Contact

Nicholas Walker
510-600-7025
nwalker@herbert-abs.com