Abstract
Wall-pressure fluctuations and surface displacements were investigated using a flexible tube which has the ability to reduce turbulent drag. Strong correlation of wall-pressure fluctuations and surface displacements were observed. Spectra of wall-pressure fluctuations of flexible tube, which were integrated in a range of non-dimensional frequency between 0.006 and 0.02, keep the lower level comparing to rigid tube. Reduction ratios of the integrated spectra show the similar trend to what drag reduction ratios do for Reynolds number tested.
