Session: 16-01-01: NSF-funded Research (Grad & Undergrad)

Paper Number: 76911

Start Time: Wednesday, 02:25 PM

76911 - Wave Simulators for Rapid Wave Formations 

Oceanic extreme waves, popularly known as rogue waves have long been a source of enigma among marine folklore and have garnered a considerable amount of interest among researchers across the globe over the last two decades or so. These waves, whose amplitude exceeds twice the significant height of the surrounding waves, appear suddenly on the ocean surface, and occur much more frequently than was previously thought. Owing to the devastating impact such events have on the oceanic environment, significant amount of research has been devoted towards investigating the reasons behind the same. However, the mechanisms governing the occurrence of such extreme events have still not been fully understood. Numerical wave simulators can play a huge part in understanding the complexity of these events and can provide with an excellent alternative to real-world experiments especially when resources and scale effects are considered. Crucial to such numerical simulation studies is the problem of generation and propagation of waves that can remain stable over the entire domain and the duration of the simulation.  

In this context, Lagrangian particle-based methods have been widely used over the last few decades for the understanding of hydrodynamic flows in coastal and marine engineering. These methods have been used for simulations of free surface flows and complex wave phenomena.  Despite the advantages, these methods also tend to suffer from instabilities. To address this, numerical investigations have been carried out by using Weakly Compressible Smoothed Particle Hydrodynamics (WCSPH) to study the influence of different kernel functions and numerical dissipation schemes to gain a better insight into the instabilities that are observed in such methods. General Process Graphics Processing Unit (GPGPU) has been utilized to overcome the computational complexity associated with the method and reduce the computational expense. The different schemes have been validated by using results from experiments occurring over small domains. Further, numerical wave tank simulations have been carried out to compare the effectiveness of the different kernel functions and the dissipation schemes by using comparative studies with theoretical results. Measured wave characteristics from these simulations like wave height and energy has showed encouraging agreement with the theoretical results. During the course of these simulations, parametric studies have been conducted to explore the sensitivity of the method to different parameters. Numerical dissipation, which is relevant for the functioning of the method has also been investigated through energy studies based on different kernel functions and dissipation schemes.

The recorded observations and results from the wave tank studies carried out by using this physics-based simulation method have been used to compare the suitability of the different kernels and dissipation schemes for devising wave tank experiments involving medium and long propagation distances for large periods of time. The findings can be utilized in the future for wave tank experiments directed at studying extreme waves and extreme energy localizations in hydrodynamic environments. The simulations can be extended to three dimensions through the implementation of improved parallelization techniques. Such studies are expected to facilitate a better understanding of the underlying mechanisms behind the formation of rogue waves and rapid large wave formations in oceanic environments.

Presenting Author: Samarpan Chakraborty University of Maryland, College Park

Authors:

Samarpan Chakraborty University of Maryland, College Park
Balakumar Balachandran University of Maryland, College Park