Laminar incompressible flow around a NACA0012 airfoil placed in a free-stream at various incidences has been revisited with the use of a fully-Lagrangian meshless method based on a Smoothed Particle Hydrodynamics (SPH) formulation. Spatial adaptivity has been incorporated in the scheme via splitting and merging of SPH particles employing zonal criteria. In addition, a novel algorithm has been proposed here so that particle merging may be achieved, ensuring the robustness, accuracy and efficiency of the computational simulations. The results obtained have been benchmarked against available data from mesh-based methods. Good agreement has been found both in steady and unsteady flow regimes. Overall, the present work demonstrated the effectiveness and competitiveness of this meshfree approach for detailed studies in aerodynamics.