Hilbert Diagnostics of Rayleigh-Benard Convection in Fluids
V. A. Arbuzov1, E. V. Arbuzov2, N. S. Bufetov3, E. O. Shlapakova4
1 Kutateladze Institute of Thermophysics, Siberian Branch of Russian Academy of Sciences Novosibirsk State Technical University
2 Novosibirsk State Technical University Sobolev Institute of Mathematics, Siberian Branch of Russian Academy of Sciences
3 Kutateladze Institute of Thermophysics, Siberian Branch of Russian Academy of Sciences Novosibirsk National Research State University
4 Novosibirsk State Technical University
arbuzov@itp.nsc.ru
Keywords: optical diagnostics of flows, Hilbert optics, Rayleigh-Benard convection, thermography of RBC structures
Pages: 61-67
Abstract
An combined optical and thermal imaging experimental system was designed to investigate Rayleigh-Benard convection of a fluid in a layer with two rigid isothermal boundaries and a free upper boundary under steady and unsteady thermal boundary conditions. The fluid surface structure was visualized using methods of reflected-light Hilbert optics. Noncontact control of the fluid layer thickness was performed using a specially designed remote meter based on an MBR-1 microscope with a smooth focusing unit based on the Meyer mechanism. The evolution of the dynamic structure of the surface and temperature field of the fluid being analyzed were studied experimentally, and the existence of flows in the form of two-dimensional rolls with axes of rotation parallel to the lateral boundaries (the walls of the cavity) was confirmed. It is shown that the highly viscous fluid flow has a thermal gravitational nature. Correspondence is found between the evolution of the thermograms and Hilbert schlieren patterns of surface structures in different modes of Rayleigh-Benard convection.
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