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Optimization and Computational Fluid Dynamics - Department of ...

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256 Marco Manzan, Enrico Nobile, Stefano Pieri <strong>and</strong> Francesco Pinto<br />

Channel (a) f =0.417 Nu = 9.90<br />

Channel (b) f =0.427 Nu = 9.96<br />

Channel (c) f =0.436 Nu = 10.04<br />

Fig. 8.18 Selected NURBS-based channels: fluid-dynamic (left) <strong>and</strong> thermal (right) fields.<br />

These three channels correspond to designs marked in Fig. 8.14; see also Fig. 8.19<br />

8.8.4 Three-dimensional Analysis<br />

This part <strong>of</strong> the work is a pro<strong>of</strong>-<strong>of</strong>-concept in 3D applications. A true optimization<br />

has not been performed on NURBS channels but, due to time<br />

limitation <strong>and</strong> computing resources available, a parametric analysis has been<br />

done in order to verify the applicability <strong>of</strong> the method to 3D problems. For<br />

the same reasons, the Reynolds number has been reduced from 200 to 100,<br />

in order to guarantee an adequate level <strong>of</strong> numerical accuracy. Therefore, the<br />

2D Pareto fronts have been recomputed at this reduced value <strong>of</strong> the Reynolds<br />

number, in order to compare the performances <strong>of</strong> the 2D channels with the<br />

3D ones. These have been obtained, as indicatedinFig.8.2,byextrusion,<br />

at different angles, <strong>of</strong> selected 2D channels. In Figs. 8.21(a) <strong>and</strong> 8.21(b), the<br />

results obtained are presented. In particular, the results for the simpler channels<br />

with linear piecewise walls are shown in Fig. 8.21(a), while the objective<br />

functions for the NURBS-based channels are shown in Fig. 8.21(b). From the<br />

figures it is evident that, for both type <strong>of</strong> channels, the Nusselt number in

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