Nowadays, hemodynamics of cardiovascular networks can be non-invasively analyzed by means of numerical simulations. Such method, based on patient-specific clinical images, represents a very useful instrument in diagnoses of vascular diseases and post-surgical follow-ups. To make the numerical model and also the results as realistic as possible and describe properly the blood flow, suitable boundary conditions are required. The purpose of this thesis is to evaluate the impact that inflow velocity profile shape has on hemodynamic results. In order to do that, left coronary circumflex clinical images of 6 subjects that underwent invasive coronary cineangiography after heart transplant with no sign of atherosclerosis provided by Città della Salute e della Scienza hospital (Turin, Italy) were considered.