1. A computer-implemented method of simulating or optimizing an occlusive procedure, the method comprising: obtaining a patient-specific anatomic model of a patient's vasculature; obtaining an initial computational model of blood flow through the patient's vasculature based on the patient-specific anatomic model; determining an occlusive procedure for treatment of the patient's vasculature; determining one or more outlets, surfaces, or boundaries of the patient's vasculature associated with or created by the occlusive procedure; modifying the initial computational model of blood flow based on the determined one or more outlets, surfaces, or boundaries; modeling redistribution of blood flow based on the occlusive procedure using the modified initial computational model of blood flow; generating a post-treatment blood flow characteristic using the modeled redistribution of blood flow; and outputting a representation the post-treatment blood flow characteristic.