Abstract
The purpose of the present study is to reveal the mechanism of amplified drag by flow acceleration. By using a multi-fan wind tunnel, we produced two kinds of unsteady flow. First, we performed experiments using rapid accelerations. fter the acceleration, a transient drag larger than the steady drag appeared for any case. Next, we performed another experiment using a sinusoidally pulsating flows with different frequencies. Comparing theoretical and experimental values, the added mass coefficient and the Basset-history coefficient were obtained by Odar's method. Using this one-dimensional formula, theoretical drags due to a rapid acceleration were obtained, and were compared with measurements.
