| Wed April 25th 2012 16:00 HR W121 | Seminar | Rayleigh-Benard Turbulence Richard Stevens |
Details:Turbulence is seen as one of the last outstanding unsolved problems in classical physics. In the last century, great minds as Heisenberg, von Weizsa ̈cker, Kolmogorov, Prandtl, and G.I. Taylor had worked on it, and Einstein put his last postdoc Bob Kraichnan on the subject of turbulence – a task which Kraichnan never finished. The rapid development of experimental and numerical techniques in this area and the growth of computing power creates a lot of activity on turbulence research. In turbulence problems encountered in the real world the influence of walls is very important and one of the classical systems to study concepts in fluid dynamics is the Rayleigh-Be ́nard (RB) system, i.e. the buoyancy driven flow of a fluid heated from below and cooled from above, see figure 1a and figure 1b. Also from an applied viewpoint, thermally driven flows are of utmost importance. Examples are thermal convection in the atmosphere, in the ocean, or in process technology.Rotating turbulent flow is of utmost importance to optimize industrial applications such as the efficient separation of carbon dioxide (CO2) from nitrogen in the emission gases of conventional carbon-based power plants to enable long term CO2 storage or the separation of CO2 from natural methane gas. In both cases the method of choice is pressurization and cooling down of the gas mixture so that finally CO2 condensates into droplets and can be separated in so-called rotational phase separators. Due to the droplet condensation, considerable heat transfers emerge in this process which are strongly affected by rotation. In this presentation experimental I will present experimental, numerical and theoretical results on RB convection. Simulations and experiments on RB convection are complementary. In accurate experimental measurements of the heat transfer a completely isolated system is needed. Therefore, one cannot visualize the flow while the heat transfer is measured. On the positive side, in experiments one can | ||
