1. A computer implemented method for assessing an arterio-venous malformation (AVM), the method comprising: receiving a patient-specific three-dimensional anatomic model of a portion of an anatomy of a patient, including one or more blood vessels having one or more vessel walls; identifying, using a computer processor, one or more blood vessels of the patient-specific model associated with the AVM; performing a blood flow simulation through the one or more identified blood vessels having the one or more vessel walls of the patient-specific three-dimensional anatomic model; calculating one or more vessel wall properties of the one or more vessel walls, comprising intramural stresses or wall stresses, using the blood flow simulation and a stress equilibrium equation; estimating a risk of an undesirable outcome caused by the AVM based on the calculated vessel wall properties; and evaluating one or more treatments of the AVM, by modifying the patient-specific three-dimensional anatomic model and performing a second blood flow simulation through the modified patient-specific three-dimensional anatomic model, wherein the evaluating comprises first identifying larger blood vessels of the AVM for intervention.