This paper is devoted to a code verification exercise for the unstructured finite-volume CFD solver ISIS-CFD. This exercise is limited to the verification of the 2D Navier-Stokes solver by prescribing a turbulence eddy-viscosity. The unstructured code is tested using three different types of grid, namely a Cartesian grid, an unstructured triangular grid, and an unstructured quadrilateral grid generated by HEXPRESS. For each type of grid, the order of accuracy of the numerical scheme is determined based on a set of 6 grids and compared to the theoretical order of accuracy. Convergence behaviour of the code on different grids is analysed.