Piston-driven pulsating flow is a specific type of pressure-driven pulsating flows. In this study, piston-driven laminar pulsating flow in a pipe is studied. This study mainly consists of two parts: developing flow and fully developed flow. In this part, hydrodynamically developing flow is examined numerically. A commercially available CFD package, FLUENT, is used in the simulations. A constant value of the time-averaged Reynolds number is considered, Re = 1000. The piston velocity is incorporated into the inlet velocity profile at the inlet. Effect of the pulsation frequency on the friction coefficient as well as axial velocity field is obtained. (C) 2014 Elsevier B.V. All rights reserved.