Abstract: The Scale-Adaptive Simulation (SAS) model has been applied to numerical simulation for steady and unsteady flows. By using SAS, the problem of velocity profiles within the boundary layer deviating from the law of wall during the process of grid refinement using traditional Detached Eddy Simulation method (DES) could be avoided. Meanwhile, this method displays the LES-like characteristics because of the effect of the automatic adjustment of scale in SAS, which makes it possible that the method avoids any non-physics and detects the local pulsation well. In the simulation of the boundary layer of flat plate at a high Reynolds number, the velocity profile within the boundary layer matches excellently with theoretical values, which illustrates that this method does not deviate from the RANS model in solving steady flows. The study case of two tandem circular cylinders shows that SAS predicts the pressure distribution at the surfaces of cylinders more accurately than other steady and unsteady flow models. Furthermore, Q contours show its LES-like characteristics. Therefore, the numerical results prove that the SAS method can be applied to engineering practice.