The levels of experimental factors are shown in Table 6. Commonlyused three-level orthogonal tables include L9(q4), L18(q7),and L27(q13). Based on the selection principle for orthogonal tables[38], L18(q7) is adopted in this paper. Each experiment in theorthogonal table is simulated by Fluent and the results correspondingto qV are given in Table 7.From the orthogonal experiment results, 15 randomly selecteddata points are used as training data set and 3 other data pointsare used as test data. The Levenberg-Marquardt algorithm is usedto train the network in the training function. The process of similartaxisand dissimilation is shown in Fig. 17. After several similartaxisoperation cycles, in Fig. 17(a) and (b), scores of the initialsuperior and temporary subgroups become constant. This meansthat each of these subgroups is mature. Comparing Fig. 17(a) and(b), it is found that the scores of initial temporary subgroups subgroup1, subgroup 2, and subgroup 3 are higher those of the initialsuperior subgroups subgroup 2, subgroup 4, and subgroup 5.Hence, the dissimilation operation is conducted thrice and 3 newsubgroups are added to the temporary subgroups. In Fig. 17(c), itcan be observed that the score of each subgroup remains constantin the similartaxis process, which means that these subgroups aremature. Comparing Fig. 17(c) and (d), it can be noted that thescores of temporary subgroups are lower than those of superiorsubgroups and therefore the dissimilar operation is no longer executed.In this instance, superior subgroups have already beenadded to the global billboard.