OPTIMIZATION OF MULTIPLE-PANEL COMPLIANT WALLS FOR DELAY OF LAMINAR-TURBULENT TRANSITION

PREVIOUS theoretical work has led to the development of methods for optimizing compliant-wall properties to achieve the greatest possible transition delay for flat-plate boundary-layer flows. It was found that the optimum wall properties for locally reducing the growth of disturbances depend quite strongly on the Reynolds number. This suggests that it would be advantageous to use multiple-panel walls with each compliant panel optimized for a particular Reynolds number range. Accordingly, the optimization procedure is extended to two-panel compliant walls, and the optimum wall properties are determined that correspond to the greatest transition delay. It is found that, based on a conservative value of n = 7, the e(n) method predicts that the greatest transitional Reynolds number achievable using single- and two-panel compliant walls is respectively 4.6 and 6.05 times the rigid-wall value. The corresponding wall properties are readily realizable for operation in water, but are probably not feasible in air.