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Numerical Simulation of Time-dependent Mixed Convection in a Horizontal Rectangular Channel
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Flow Pattern Selection and Unsteady Effects for Mixed Convection in a Horizontal Rectangular Channel
No full textThe three-dimensional, time-dependent mixed convection in
horizontal rectangular ducts, heated from below, is numerically
investigated with a time-accurate, finite volume projection method.
The accuracy of the numerical model is critically assessed by comparison of the computed results with the experimental measurements obtained in a channel with high width/height aspect-ratio, and values of Reynolds number Re = 42, Grashof} number Gr = 6884 and Prandtl} number Pr = 0.71. The thermally developing, mixed convective flow in a channel of width/height = 2 is computed for Re = 10, Pr = 0.71 and values of Gr/Re^2 in the range 50-1000.
It is found that, irrespective of the Gr value considered, transverse traveling waves are always present at the startup of the heating process. However, for the lower values of Gr considered, Gr = 5000 and 10000, at later times they are eventually swept away, giving rise to a steady longitudinal rolls pattern. At higher values of the Grashof number, Gr = 15000, the persistance of such transverse waves, results in unsteady modulations of the longitudinal vortex rolls.
For Gr = 1x10^5, the flow is characterized by a chaotic combination of transverse waves, and ascending/descending plumes and thermals
The natural and cultural heritage of the Serra de Estrela, between UNESCO geopark and lithium mining
No full textWith a review of the academic and journalistic literature, this chapter aims to further explore the shift toward a sustainable tourism in the context of UNESCO Natural Parks and Geoparks. Furthermore, the authors point out the persistence of a contradiction, that is, the presence of mining activities in the surrounding of above-mentioned UNESCO areas. After briefly reconstructing the socio-economic history of the mountain area of Serra da Estrela, located in the region of Beira Interior, in Central Portugal, the authors focus on the tension between two aspects: 1) the Post-Fordist model, concerning the transition to tourism development related to creation of UNESCO Natural Park and Geopark and 2) the reinforcement of lithium mining production and discovery of new deposits as an energetic and economic strategy for Portugal. In particular, the latter issue has given rise to various groups and movements of protest on a local basis. The claims of these groups suggest a radical paradigm shift in the development plans and in the conception of heritage in an ecological sense
Numerical Simulation of three-dimensional Time-dependent Buoyant Flows on the T3D
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Large-Scale Simulation of Time-Dependent Three-Dimensional Buoyant Flows
No full textThis study describes a numerical procedure designed for large-scale simulation of 3D, time-dependent buoyant flows. The algorithm is based on a time-accurate, Finite Volume implementation of a 3nd order Projection scheme. Careful design of the data-structure has allowed the parallelization of the entire algorithm on a Cray T3D computer. Preliminary results are reported, namely the characteristic quantities, obtained for 3D natural convection in a cubic cavity, and the comparison between numerical results and experimental measurements for the mixed convection flow in a bottom-heated horizontal rectangular channel. It is concluded that the proposed algorithm is accurate and efficient, and it will give the opportunity to perform direct large-scale simulations of 3D, time-dependent and turbulent buoyancy-dominated flows
Hybridisation of a multi-objective genetic algorithm, a neural networks and a classical optimiser for complex design problem in fluid dynamics
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