The new methods of diagnosis are often more sensitive and speed up its process allowing for a more effective treatment. Yet they need to be carefully tested before they can be used in practice. The paper concerns the problems of developing nanorobots, which would circulate in the bloodstream of the human body gathering information about its condition. Simulation of these new ways of diagnosis is the main motivation behind the presented work. Introduction of such nanorobots into the bloodstream puts several requirements on their mechanical properties. Thus, our first goal is to build a model to simulate the blood flow with nanorobots present in the capillary vessels and medium-sized blood vessels. We split it into two separate initial models and implementations. The first one is a simulation of the blood flow using particlebased methods in order to determine the appropriate mechanical parameters of nanorobots and verify their behavior. The second one is a multi-agent simulation that will allow to evaluate the usefulness of the data collected and prototype the system performing functions of nanorobots within the specified constraints.