An initial set of individuals having design parameters of a blade as a gene,
is
determined at random (S12). Next, an analysis using Navier-Stokes equations
is performed. On the basis of the analysis result, ranking (evaluation) of respective
individuals are performed using a pressure loss coefficient, a trailing edge deviation
angle and the like as objective functions (S14). When a shape of a blade
having a desirable performance is obtained, or when a predetermined number of generations
is achieved, the analysis is terminated assuming that a termination condition has
been met (S22). When the termination condition has not been met, processes
about individual selection, crossing between individuals and mutation are performed
so that generation is incremented by 1. The above processes are repeated, so that
Pareto solutions can be obtained according to MOGA in consideration of a trade-off
relationship between the objective functions.