Experimental studies are made of the fluid flow and mass transfer from a circular cylinder in a pulsating flow. The oncoming free-stream velocity contains a pulsating component, $U=U_0(1+cos2\pi f_pt)$, where the pulsating flow was generated by an woofer speaker located at the wall of a wind-tunnel settling chamber. The mass transfer rate was scrutinized over broad ranges of the two externally-specified parameters, i.e., the pulsation amplitude (0.8(%) ≤ $A_0$ ≤ 25(%)) and the pulsating frequency(10(Hz) ≤ $f_p$ ≤ 40(Hz)). The naphthalene sublimation technique was employed to measure the circumferential mass transfer rate around a circular cylinder. The Reynolds number was varied, 4,150 ≤ $Re_d$ ≤ 12,450. As the pulsating frequency $f_p$ and amplitude $A_0$ increase, a remarkable enhancement of mass transfer was observed, especially in the wake region. The mass transfer enhancement in the main vortex region of the wake region was more conspicious than that in the second vortex region. As $A_0$ increases to larger values than a moderate value where lock-on occurs, the wake structure was well-organized. In the range where lock-on occurs, the increase of mass transfer was more pronounced in the wake region than the case where lock-on does not occur. The relative effect of pulsation on mass transfer was found to be decreased with increasing the Reynolds number.
