Two-dimensional numerical simulations of low-speed flow past close-coupled tandem NACA0012 airfoils are presented. A sinusoidally plunging airfoil is placed at 0.1c downstream of a stationary airfoil to investigate how the interaction of the wake of the forefoil and hindfoil affects the unsteady flowfield and the aerodynamic performance of the tandem airfoils at various freestream velocity, plunge amplitude, plunge frequency and wide range of low Reynolds numbers from 2090 to 59710. Unsteady Reynolds-averaged Navier–Stokes solutions are obtained by using the transition shear-stress transport γ-Re_θ turbulence model. The flow over a single plunging airfoil is also simulated for comparison. These analyses show that the numerical solutions predict a significant thrust augmentation in stationary/flapping airfoil combinations in tandem. This augmentation is associated with the strengthening of the leading-edge vortex in the tandem airfoils, and the difference in thrust is mainly observed at the equilibrium position due to obtaining the maximum effective angle of attack here. Also, the thrust of the hindfoil and tandem airfoils are very close since the drag produced by the stationary forefoil is relatively small compared to thrust at vp nearly larger than 1. On the other hand, the propulsive efficiency of the hindfoil and single airfoil is generally equivalent but considerably larger than the tandem airfoils.