The designs for large civil engineering structures (LCES), e.g., long-span suspension bridges, guided towers/masts, hydraulic/wind driven turbines, deep water risers and offshore fixed/floating platforms are usually governed by wave and/or wind loading. The objective of this project is to educate students and advance research in water waves and fluid-structure interactions (FSI) in relation to the analysis and design of LCES. In particular, the aim is to advance computational modeling of breaking water waves and high Reynolds number (Re) flows because model-scale tests used in today.s design cannot reproduce full-scale structural behavior. Due to this fact, the most common vibrations problems on LCES are those induced by vortex shedding, that is, both wind flow and wave/current loads. Although previous investigations have been done, unresolved issues remain to be investigated of the interactions of density stratified multiphase fluids and fluid-solid mechanisms. This is especially true when the free-surface becomes unstable and breaks and for fluid structure mechanisms with high Re. This project is concerned with these interactions as they could be responsible for loss of structural integrity and even failure. To this end, numerical models can prove to be valuable tools in analyzing and understanding the mechanisms of free surface instabilities and FSI. However any method that can provide aid should be used, including, theoretical, experimental and/or computational methods. But computational model development is prioritized mainly because it is believed that new discoveries can be made in free-surface instabilities and high Re incompressible flows around bluff-bodies.
Intellectual merits: A principal challenge to be addressed is that of moving interfaces, as well as the multitude of scales in the flow. The project is concerned with investigations of breaking water waves and vortex induced resonance problems of LCES. This project is driven by the following core ideas: 1) Extending the Lattice Boltzmann (LB) equation to model breaking ocean waves numerically; 2) Numerically predicting vortex induced resonance on LCES using an extended LB formulation; 3) Developing an interdisciplinary FSI course. Civil engineering students will especially benefit; 4) Using a virtual reality laboratory in teaching and research.
The LB approach, which is based on statistical mechanic concepts, obeys Navier-Stokes equations. It has been used extensively in molecular dynamics and physics but has not been developed in relation to LCES. To the PI.s knowledge, this is the first time a LB model is being developed to simulate breaking ocean waves and their interactions with LCES. It is also the first time a LB formulation contains FSI, turbulence and nonlinear free-surface model capabilities. The fundamentals of the model approach have several attractive features, especially with regard to free- surface breaking waves, FSI and parallel solver development. The unsteady flows of interest are highly three-dimensional and are further complicated by the interaction with a fixed or oscillating structure. Therefore, to improve the learning process for students and researchers at all levels, emphasis on visualization programming in a virtual reality laboratory to analyze the results of the models is proposed. Furthermore, as a supplementary project component, the computational models will be validated with planned flow field measurements and visualization experiments. Free-surface physical experiments are planned and will mainly comprise monitoring sloshing motion in tanks. The bluff-body aerodynamics experiments will focus on simultaneous measurements of structural movement and the wind field. Collaborators will also provide data from both computational and physical experiments.
Broader Impact: Although the research part of the project focuses on one particular fluid formulation, the core idea of this project evolves around improving methods of design of LCES through detailed modeling of fluid flows and the coupling between fluid and solid. The career development plan of the PI has, however, highly interdisciplinary contents making it applicable beyond civil and mechanical engineering. FSI and wave dynamics modeling are important topics in many disciplines, such as computer science; astrophysics; biomedical engineering and earth science. The computational models proposed herein will apply to these other fields of science. It is the PI.s career goal to model problems and contribute in these other areas as well when the computational fluid dynamics groundwork related to LCES has been explored. Furthermore, wave dynamics and FSI research and education is important to society as it could save lives by avoiding structural collapse. A project of this kind also plays an important role in energy development, economic development and in the nation.s balance of payments problems.
