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IIHR Seminar: Betsy Seiffert

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June 8 @ 1:30 pm - 2:30 pm

| Free

Simulation of breaking waves using the High-Order Spectral method

Presented By:
Betsy Seiffert,
Assistant Professor,
Department of Ocean and Mechanical Engineering,
Florida Atlantic University

ABSTRACT: We examine the implementation of a wave-breaking mechanism into the non-linear potential flow solver HOS-NWT. This model is a computationally efficient, open source code that solves for the free surface in a numerical wave tank using the High-Order Spectral (HOS) method. To solve for wave-breaking in this model, first a wave-breaking onset parameter is identified, and then a method for computing wave-breaking associated energy loss is determined. Wave-breaking onset is calculated using a kinematic criteria and wave-breaking energy dissipation is calculated by adding a viscous diffusion term computed using an eddy viscosity parameter, which is estimated based on the pre-breaking wave geometry. A set of two-dimensional experiments is conducted to validate the implemented wave breaking mechanism at a large scale. Excellent agreement between calculations made using HOS-NWT and experimental measurements for surface elevation and corresponding frequency/amplitude spectrum, as well as energy dissipation, suggest the model is accurately calculating wave-breaking onset and wave-breaking associated energy dissipation for a wide range of conditions. Although the current study is limited to a unidirectional wave field, the success of the wave-breaking model presented provides the basis for application of the model in a multidirectional wave field. By including wave-breaking energy dissipation into HOS-NWT, we can increase the application range of the model, as well as decrease the occurrence of numerical instabilities that are associated with breaking waves in a potential flow solver. An accurate description of the wave field is useful for predicting the dynamic response of offshore vessels and marine renewable energy devices, predicting loads on marine structures and the general physics of ocean waves, for example.

Details

Date:
June 8
Time:
1:30 pm - 2:30 pm
Cost:
Free

Venue

Stanley Hydraulics Lab
127 SHL
Iowa City, IA 52242 United States
Phone:
319-335-5237
Posted on May 23rd, 2017

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