Passive Drag Reduction Technologies

The developments and involved factors of mature passive drag reduction technologies, i.e., compliant coating, superhydrophobic surfaces, and epoxy coating, are reviewed. Alterations in critical Reynolds number are observed in the presence of passive drag reduction technologies. With the advancement in technology, numerical approaches are introduced to lower the cost and achieve better understanding of physical phenomena such as lowering energy, flow control, designing the surfaces of materials, and so on. Experimental results as well as numerical results are stated. The effects of factors like wetting, contact angle, contact angle hysteresis, roughness, pot life, and coating aging responsible for drag reduction are also briefly presented with numerical and experimental perspective analyses.