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Optimization and Computational Fluid Dynamics - Department of ...

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

<strong>Optimization</strong> TOOL<br />

Scheduler<br />

FALSE<br />

Fig. 8.11 <strong>Optimization</strong> work-flow<br />

Define initial set<br />

<strong>of</strong> designs(population)<br />

by DOE<br />

Define<br />

Input/Design<br />

variables<br />

SOLVER<br />

Bbuild geometry<br />

generate mesh<br />

ssolve<br />

forced<br />

Cconvection<br />

problem<br />

compute f <strong>and</strong> Nu<br />

Output<br />

objectives<br />

Stop<br />

condition<br />

TRUE<br />

Post-processing<br />

there is an ample variety <strong>of</strong> numerical techniques to perform optimization<br />

tasks. EAs are the most robust ones, <strong>and</strong> have been used in this optimization<br />

process. In particular, MOGA-II algorithm, has been employed.<br />

The optimization process, sketched in Fig. 8.11, follows these tasks:<br />

• Automatically the optimization s<strong>of</strong>tware generates a set <strong>of</strong> numbers, i.e.,<br />

the geometrical design variables, representing the shape <strong>of</strong> a channel<br />

(called individual).<br />

• These variables are written in an input file, which is sent to the CFD<br />

solver. This, in turn, computes the flow <strong>and</strong> thermal fields, <strong>and</strong> from these,<br />

it evaluates the friction factor <strong>and</strong> the Nusselt number, which represent<br />

the objective functions.<br />

• The numerical values <strong>of</strong> the objective functions are sent back to the optimizer,<br />

which generates another set <strong>of</strong> geometrical parameters.

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