Topical Problems of Fluid Mechanics


Institute of Thermomechanics AS CR, v.v.i.	CTU in Prague Faculty of Mech. Engineering Dept. Tech. Mathematics	MIO Université du Sud Toulon Var - AMU - CNRS - IRD	Czech Pilot centre ERCOFTAC

Mixing in Convective Thermal Fluxes in Unsteady Non-Homogeneous Flows Generating Complex Three Dimensional Vorticity Patterns
Redondo J. M., Tellez J. D., Sanchez M. A., Lopez Gonzalez-Nieto P.
Abstract:
Diffusion and scaling of the velocity and vorticity in a thermoelectric driven heating and cooling experimental device is presented in order to map the different patterns and transitions between two and three dimensional convection in an enclosure with complex driven flows. The size of the water tank is of 0.2 x 0.2 x 0.1 m and the heat sources or sinks can be regulated both in power and sign [1-3]. The thermal convective driven flows are generated by means of Peltier effects in 4 wall extended positions of 0.05 x 0.05 cm each. The parameter range of convective cell array varies strongly with the Topology of the boundary conditions. Side heat and momentum fluxes are a function of Rayleigh, Peclet and Nusselt numbers, [4-6] Visualizations are performed by PIV, Particle tracking and shadowgraph. The structure of the flow is shown by setting up a convective flow generated by buoyant heat fluxes. The experiments described here investigate high Prandtl number mixing using brine and fresh water in order to form a density interface and low Prandtl number mixing with temperature gradients. The evolution of the mixing fronts are compared and the topological characteristics of the merging of the convective structures are examined for different configurations. Based on two dimensional Vorticity spectral analysis, new techniques can be very useful to determine the evolution of scales considering the multi-fractal structure of the convective flows.
Keywords:
vorticity, thermoelectric convection, PIV, scaling structure, turbulence

Fulltext: PDF DOI: http://dx.doi.org/10.14311/TPFM.2016.022

In Proceedings Topical Problems of Fluid Mechanics 2016, Prague, 2016 Edited by David Šimurda and Tomáš Bodnár, pp. 161-168 ISBN 978-80-87012-58-1 (Print) ISSN 2336-5781 (Print)