1. A method for planning and guidance of tumor ablation therapy in a target organ based on a patient-specific model, comprising: estimating a patient-specific anatomical model of the target organ and a circulatory system of the target organ from medical image data of a patient; simulating blood flow in vessels and porous regions of the target organ based on the patient-specific anatomical model; simulating heat diffusion due to ablation based on a virtual ablation probe position and operating parameters and the simulated blood flow in the vessels and porous regions of the target organ considering both cooling effects from the blood follow in the vessels and the porous tissue blood perfusion; simulating cellular necrosis in the target organ based on the simulated heat diffusion; and generating a visualization of the patient-specific anatomical model with a simulated necrosis region resulting from simulating the cellular necrosis.