Blood flow in an aortic arch with aneurysm was simulated numerically by using a commercial CFD solver, STAR-CD. The difference in flow field perfused from two different cannulae, i.e., curved end-hole and dispersion cannulae was analyzed in detail. The numerical models of aortic arch and cannula were independently reconstructed from CT images. The cannula model was then inserted, with appropriate position, depth and angle, into the aortic arch model. It was found that the perfusion velocity from dispersion cannula was smaller than that from the curved end-hole cannula because of greater attenuation in typical filmy jet flow from dispersion cannula. This filmy jet flow decreases maximum wall shear stress on the inner surface of aortic arch by one-fifth compared to the straight jet flow perfused from the end-hole cannula.