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Optimization and Computational Fluid Dynamics - Department of ...

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

L/2<br />

�in<br />

(a) (b)<br />

L<br />

�out<br />

h<br />

y<br />

�<br />

�<br />

�<br />

i<br />

j<br />

4<br />

x<br />

1 2 3 7 8 9<br />

(c) (d)<br />

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Lwave<br />

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Fig. 8.5 Periodic channels <strong>and</strong> geometrical parametrization. (a) Linear piecewise channel;<br />

(b) NURBS channel; (c) Linear piecewise parametrization; (d) NURBS parametrization<br />

<strong>and</strong> control points<br />

the linear-piecewise <strong>and</strong> the NURBS, are depicted in Figs. 8.5(a) <strong>and</strong> 8.5(b),<br />

respectively.<br />

8.5.1.1 2D Linear Piecewise Parametrization<br />

The linear piecewise wall pr<strong>of</strong>ile <strong>of</strong> the channel is characterized by a small<br />

number <strong>of</strong> design variables or Degrees Of Freedom (DOFs). Their exact meaning<br />

will be described in Sect. 8.6. Here it is sufficient to say that they represent<br />

the independent variables that may be adjusted, during the optimization<br />

process to achieve the desired goal(s). The variables introduced in this wall<br />

parametrization are presented in Fig. 8.5(c) <strong>and</strong> summarized in Table 8.1.<br />

There are four DOFs requested for describing the wall pr<strong>of</strong>ile. Realized by<br />

defining a set <strong>of</strong> points <strong>and</strong> connecting them with straight lines, the pr<strong>of</strong>ile is<br />

constructed only for convenience in order to have the edge <strong>of</strong> the corrugation<br />

centeredonthewall.<br />

5<br />

6

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