Invited Speakers

Prof. Enrico Foti (University of Catania, Catania, Italy)

Wave and current generated sea ripples: experimental results and open questions
In coastal regions the combined action of waves and currents generates a complex flow that often leads to the formation of small scale sedimentary structures known as ripples. The bedform evolution, their equilibrium conditions as well as migration velocity have been thoroughly studied theoretically and experimentally in the last decades. In fact, it is well known that ripple appearance strongly influences the bottom roughness with repercussions on sediment transport, mixing processes, wave dissipation etc. Recent research has been focused on the consequences that waves, coexisting with collinear or orthogonal currents, even if wave-generated (such as in the case of a sloping bed), can assume in enhancing flow non linearities, and on the hydro-morphodynamics mutual effects.
In the case of codirectional waves and currents, experimental findings indicate that along a sloping beach, a wave induced offshore directed steady current superimposes on waves, turning ripples towards a strong asymmetry and leading to an offshore migration. The turbulence is non-negligible, particularly during the onshore directed half cycle, due to flow asymmetry. Turbulence causes a considerable flow stirring which, above a non-cohesive bed, could lift the sediment up in the water column and give rise to a strong sediment transport.
Recent experiments dealing with orthogonal waves and currents over a rippled bed show that combined flow not only may modify the bedform geometry but it also undergoes a strong modification in terms of vortex dynamics and boundary layer structure in the proximity of the bottom.
Many aspects however are still open, i.e. the influence of wave dominated or current dominated conditions on bed roughness, the change of turbulence structure, the wave generated steady current vertical profile, making this topic particularly fascinating for future researches.

Enrico Foti is a Professor of Hydraulics at the University of Catania (Italy). Obtained the Degree in Hydraulic Engineering at University of Catania with 110/110 summa cum laude in 1989. In the same year he was awared the "Ordine degli Ingegneri della Provincia di Catania" award for the best thesis in Civil engineering at the University of Catania. In 1989-1990 he was researcher at the European Center for Scientific and Engineering Computing of the IBM developing lattice gas models for studying flows in porous media. Then he completed his doctoral work at the University of Genova and his postdoctoral work at the Department of Naval Technologies of Genova of the National Research Council (CNR). He is Author and coauthor of more than 100 research papers published in referred journals or at national and international congresses on topics also regarding sediment transport, grain sorting and small scale morphodynamics. He was Chairman of the EUROMECH Colloqium n.451 on "Sea wave bottom boundary layer" held in Taormina, 26-29 October 2003.

Prof. Jason Butler (University of Florida, Gainesville, FL, USA)

Dynamics and Alignment of Fibers in Oscillatory Shearing Flows
Fibers suspended in a viscous, Newtonian fluid can be aligned perpendicular to the flow-gradient plane by applying an oscillatory shear flow.  Here, measurements and simulations of the orientation distribution are reported over a wide range of concentrations, strain amplitudes, and confinements. The fibers were rigid, non-colloidal and neutrally buoyant, and the strain amplitude and confinement were varied using a custom-built shear cell. The fibers aligned in the vorticity direction only when the concentration was sufficiently high and for a limited range of strain amplitudes of approximately 2 to 3 and gap widths to particle lengths of around 1.5. Direct comparison of simulations with experiments demonstrates that a simple model, which considers only excluded volume and self-mobilities, can accurately predict the fiber dynamics and orientation distributions for these concentrated suspensions. Analogies with other viscous and concentrated particulate systems that can be structured by oscillating the flow field are discussed.

Jason E. Butler is a Professor of Chemical Engineering at the University of Florida (Gainesville, Florida).  Dr. Butler completed his doctoral work at the University of Texas at Austin and post-doctoral work at Stanford University.  Prior to joining the faculty at the University of Florida in 2001, Dr. Butler also worked at Aix-Marseille University in Marseille, France, where he still frequently visits.  Dr. Butler's research interests encompass dynamic phenomena within complex multiphase fluids using experimental, computational, and theoretical methods.  His research in the field of complex fluids spans theoretical, computational, and experimental approaches to resolving questions that impact applications in fields such as microfluidics and slurry flows.  Among other achievements, Dr. Butler has contributed to the theory and modeling of sedimentation and rheology of non-spherical particles, the Brownian dynamics of rigid polymers and Brownian rods, and the electrokinetics of polyelectrolytes.

Prof. Daniel Ahmed (ETH, Zurich, Switzerland)

Acoustic Oscillation-induced Micro/nanorobots for Applications in Life Sciences and Healthcare
A high-frequency acoustic field at moderate levels of pressure is regarded as a safe, non-invasive, and relatively inexpensive procedure for manipulating particles. The non-invasive manipulation of small entities, such as living cells, model organisms, and micro/nanorobots, is likely to become an invaluable tool in the fields of biology, biophysics, and medicine. For example, controlling small machines or micro/nanorobots can transform numerous aspects of medicine by enabling important tasks, such as the targeted delivery of drugs, performing biopsies, and use in minimally-invasive surgery. In this presentation, I will demonstrate acoustic methods to manipulate cells and organisms in controlled microfluidic devices and then discuss several examples of acoustic-based micro/nanorobots. I also will discuss a new propulsion mechanism that was inspired by neutrophils rolling on the vasculature. This mechanism will allow us to navigate particles against the flow, which, to date, has been a fundamental limitation in the field of robotics. The manipulation platforms that have been developed will have significant impacts in various fields of bioengineering and biomedical applications.

Daniel Ahmed holds a Bachelor's, Master's, and Doctoral degree (2013) in Engineering Science and Mechanics at Pennsylvania State University in the U.S. He did his postdoctoral work followed by a senior scientist position in the Institute of Robotics and Intelligent Systems at ETH Zürich. Currently, Dr. Ahmed is an Assistant Professor of Acoustic Robotics for Life sciences and Healthcare in the Department of Mechanical and Process Engineering at ETH Zürich. Daniel Ahmed's research focuses on acoustics in micro and nanorobotic and microfluidic systems to develop technologies at the interface of biotechnology, biomedical engineering and medicine. Dr. Ahmed has contributed to developing new acoustic-based micro/nano propulsion systems.