We present a cut-cell method for the simulation of 2D incompressible flows past obstacles. It consists in using the MAC scheme on cartesian grids and imposing Dirchlet boundary conditions for the velocity field on the boundary of solid structures following the Shortley-Weller formulation. In order to ensure local conservation properties, viscous and convecting terms are discretized in a finite volume way. The scheme is second order implicit in time for the linear part, the linear systems are solved by the use of the capacitance matrix method for non-moving obstacles. Numerical results of flows around an impulsively started circular cylinder are presented which confirm the efficiency of the method, for Reynolds numbers 1000 and 3000. An example of flows around a moving rigid body at Reynolds number 800 is also shown, a solver using the PETSc-Library has been prefered in this context to solve the linear systems.immersed boundary techniques have been developped by Peskin in the 80's ([26, 27]), consisting in using Dirac functions to model the interacting force between the fluid and the solid structure. These methods have inspired many authors in the following years, Mohd-Yusof has combined them with the use of B-Splines ([24]) in his momentum forcing methods to consider complex geometries. The main advantage of these techniques is that the forcing term does not change the spatial operators, making them quite easy to implement (see [23] for a review, and refences therein). As an alternative, Bruno et al. have developped penalization techniques to inforce suitable boundary conditions [1]. Similar techniques have also been investigated by Maury et al.[17] and justified from a mathematical point of view in [21]. These methods have been shown to be efficient in the context of several particles in a flow [19], and when considering possible collisions between them [32].Arbitrary Lagrangian Eulerian (ALE) methods have been developped for flows in geometries which vary in time (see [28,29,33] where authors use some of the ideas of [5]). The aim is to formulate the equation in a fixed reference domain, by using a mapping from the reference domain Ω(0) to the domain Ω(t) occupied by the fluid at time t. The position of the moving bodies, which correspond to the boundary of Ω(t), being available, the velocity field of these bodies defined on ∂Ω(t) have to be extended to Ω(t). Once this is done (generally with harmonic extensions), the equations are written in the reference domain by using the chain-rule formula.For problems involving non-rigid bodies, Roshchenko et al. (see [30]) have used splitting methods to solve first the evolution of the velocity field in the fluid, and then to consider the deformation of the body. These ideas of splitting the model can be viewed as similar to the projection techniques (see [11], and [14] for a review and references therein).The method presented in this work joints another family of methods, called cut-cell methods. The idea of these methods is to modify the discretization of the Navier-St...