Fluid Mechanics Seminar: Mohammad-Reza Alam

Free propagating water waves traveling over seabed ripples may be significantly altered if certain conditions between wave characteristics and the seabed irregularities are satisfied. This phenomenon is referred to as Bragg reflection or resonance; a name taken from the analogy to its close cousin phenomenon in solid state physics of X-ray diffraction in periodic crystals. Bragg resonance of water waves contributes to the development of coastal wave spectrum, modifies bottom features, and may explain the generation of internal gravity waves in stratified fluids. I will present recent results in oblique and high-order (nonlinear) Bragg resonance of water waves in homogeneous and stratified waters and discuss their impacts on oceanic spectral evolution. These results may have a number of practical applications in ocean engineering. Specifically I will briefly talk about how Bragg Resonance can help protecting offshore structures (such as offshore wind farms) against ocean waves, can transfer tidal current energy to the surface, and can focus ocean wave energy for high-efficiency ocean wave energy conversion. Bio: Dr. Mohammad-Reza Alam is an assistant professor of Mechanical Engineering at the University of California, Berkeley. He joined UC Berkeley in July 2011 after the completion of his Ph.D. at MIT (2008) and serving as a postdoctoral associate and lecturer also at MIT (2008-2011). His research is mainly focused on theoretical hydrodynamics and coastal waves phenomena.