The high cost of energy has resulted in a renewed interest in the study of reducing skin-friction drag in aeronautical applications. Laminar Flow Control (LFC) refers to any technique which alters the basic-state flow-field to delay transition from laminar to turbulent flow. Achieving fully laminar flow over a civilian transport wing will significantly reduce drag and fuel costs while increasing range and performance. Boundary-layer suction has proven to be an effective means of achieving laminar flow over an aircraft wing as demonstrated with the Northrop X-21 program; however, even with the savings in fuel, the high manufacturing and maintenance costs have discouraged the use of this technology. Recent work using threedimensional (3-D) spanwise-periodic distributed roughness elements (DREs) has shown great promise as a means of controlling the crossflow instability responsible for transition over a swept wing without the need for a complex suction system. The Texas A
