The acquisition supported by this Major Research Instrumentation (MRI) grant consists of a modular wave tank and related wave making and data collecting instrumentation to be housed in the new Fluids Lab at the University of North Carolina. The proposed modular wave tank has been designed with maximum flexibility in mind. Much of fluid mechanics takes place across multiple scales, and their nonlinear coupling is arguably one of the most challenging features of theoretical and experimental science. With this instrument the team of PIs and participants will be able to probe into phenomena, some of them newly discovered in the existing Mathematics Fluid Lab or in field experiments by Marine Science faculty, as never before. From mixing in stratified jets and their generation and interaction with internal waves, to sedimentation of particles in stratified fluids and their entrainment phenomena, to large internal solitary wave propagation from deep to shallow topography with forcing and breaking, to boundary layer sediment transport by surface wave motion, the host of experiments that the new instrumentation makes possible is such as to guarantee intensive usage for many years to come. The modularity of the new wave tank is designed so that each module can serve a different purpose, as well as allowing simultaneous experiments to take place in the different modules. This will optimize time sharing as well as usage of resources.
The destructive powers of water, set in motion by large natural forces, have been painfully illustrated by the tragic events that marked the recent past. Tsunamis and hurricane surges have taken untold lives, and cost hundreds of billions of dollars in damage. The primary means to mitigate the effects of these uncontrollable natural forces is accurate prediction and forecast, which in turn relies on fundamental understanding of the physical phenomena at play. Close integration of experimental and mathematical modelling is becoming more and more recognized as the most successful approach to study this range of fluids problems. The proposed instrumentation is dedicated to the study of the relevant physical processes that govern the dynamics of water emulating these natural events, with the ultimate goal of improving predictive capabilities. The visual appeal of fluid motion and the challenge of its mathematical modeling will further extend the proposed instrumentation into a primary educational tool able to attract bright undergraduate students to careers in the sciences, thereby increasing the competency of our workforce in these fields of national interest.
The MRI Modular Wave Tank, made possible by this grant, is a unique facility that lies at the core of the UNC Joint Fluids Lab (JFL), established in 2007 thanks to the support of the UNC Science Complex Construction in the basement of the new Chapman Hall building. The uniqueness of the 120' long, 13,500 gallon maximum capacity tank consists of its optically accessibility from all sides, including a glass bottom spanning the whole length, its modular design, which can compartmentalize the facility to run three different experiments simultaneously or work in unison, and its large size, which allows for studies of how mathematica models and their predictions maintain validity across scales. For instance, in this configuration the tall 12' section is capable of providing gravity feed of water to the intermediate 60' long and narrow section, which in turn empties in a wide 12' shallow section for two dimensional studies of wave-bottom and beach interactions. Several computer controlled motorized carts carry instrumentations (cameras, lasers, probes) that help collect data for a variety of experimental setups, including internal waves that form when water is stratified, by varying salt concentration, and set in motion by disturbing its equilibrium state. Since its basic completion in 2010, the facility has helped in fundamental and applied research, some featured by major media organization (CNN, New York Times, National Geographic as well local news and scientific publications) such as the research connected with the 2010 Deep Water Horizon Gulf oil spill. Researchers at UNC were able to demonstrate in the controlled JFL facilities how oil underwater plumes could form and get trapped at density transitions of ocean water columns. The MRI wave tank and JFL facilities have attracted over 100 undergraduate students as research assistants, many of whom have gone or are going on to get advanced degrees in the mathematical sciences, and has supported research by more than 10 graduate students and 7 postdoctoral researchers, with 3 Master and 5 PhD thesis to date. The wave tank has also hosted a number of educational activities, with UNC First Year Seminar courses, as well as been one of the main attraction of the UNC Science Fairs since the first of these events in 2010. Numerous NC High School and K-12 students and a large number of official delegations from academia and administrations have also been hosted and viewed demonstrations in the lab, notably those emulating the formation of large scale vortices in some of areas offshore the coasts hit by the Japan tsunami of 2011. The wave tank and general facilities centered on it in the JFL continue to grow and keep the equipment to its cutting-edge level by attracting further support. A newly awarded MRI grant will allow us to install a completely new concept of pneumatic wave making which does away with moveable rigid surfaces, such as the paddles and bobbers commonly used in labs all over the world where wave research takes place. The lab and the wave tank equipment has also expanded towards the end of 2012 by adding a storage area which allows the near total recovery of the water used in experiments, including filtering and separation of briny and fresh water streams.
