Effects of the earth's rotation on convection: Turbulent statistics,scaling laws and Lagrangian diffusion |
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| Institution: | 1. Surface Engineering Institute, RWTH Aachen University, Kackertstr. 15, D-52072 Aachen, Germany;2. Institute for Materials, Ruhr-Universität Bochum, Universitätsstraße 150, D-44801 Bochum, Germany;1. Friedrich-Alexander University Erlangen-Nürnberg (FAU), Department of Materials Science and Engineering, Institute I: General Materials Properties, Martensstr. 5, 91058 Erlangen, Germany;2. University of Rome “ROMA TRE”, Engineering Department, Via della Vasca Navale 79, 00146 Rome, Italy;3. Department of Materials Science, TU Darmstadt, D-64287 Darmstadt, Germany;1. Department of Mechanical & Aerospace Engineering, University of Strathclyde, Glasgow, G1 1XJ, UK;2. Defence and Security Research Institute, University of Nicosia, Nicosia, Cyprus;3. Air Force Research Laboratory, Wright Patterson AFB, Ohio 45433-7402, USA;4. Senior Researcher at the University of Nicosia Research Foundation, Cyprus |
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| Abstract: | The effects of Earth's rotation on convection into stratified fluid under uniform surface cooling are investigated using a large-eddy simulation (LES) model. The initial mixed layer depth varies by a factor of 40 and temperature gradient below the mixed layer varies by three orders of magnitude. At the end of integration (typically 20–40 inertial periods), the so-called natural Rossby number for the rotating experiments varies from 0.06 to 2. The wide range of conditions used is designed to extract scaling laws of rotating convection and to shed light on the importance of Earth's rotation on convection. It is found that the effects of rotation can be characterized by a series of hyperbolic tangent functions of the natural Rossby number. The effects of rotation are most pronounced when Ro is order 0.1 or less. For Ro ≥ 1, the effects of rotation become small. Comparison of Lagrangian statistics of numerical floats reveals that horizontal mixing is suppressed in the presence of rotation. This result is consistent with the finding that integral length scale and turbulent intensity decrease when rotation is included, in contrast to the conclusion of an early study that argued for increased horizontal mixing in the presence of rotation. |
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