Arterial diseases of sclerosis and aneurysm are known to be related with a local blood flow. There are indeed decades of related studies, recently being with an aid of a computational approach on a patient-specific basis, but those have yet to be translated into clinical medicine. 'Simply why?', and 'how to achieve it?' Computational blood flow originates from theoretical and computational fluid dynamics. Understanding the underlying knowledge may be beyond the scope of medical professionals. Engineers have to be fully aware of a barrier on an interface with clinical medicine, and manage to translate the evolving technology with a special focus on balancing the efficacy and safety. Visual analytics is to facilitate to overcome an academic gap between engineering and clinical medicine. This paper deals with the recent development of visual analytics of malignant blood flows in cerebral aneurysms for medical professionals.