This paper intends to simulate 3D bloodflow of carotid artery bifurcations using a suitable geometrical model with the help of various processing tools and methods. To understand flow characteristics of human bloodflow, it is essential to model 3D human arterial tree with as many branches as possible. Geometric modeling of the artery network is structured using a commercial program (Mimics). Conversion of the medical raw data to the geometrical model requires preprocessing tools and software in order to clean the distorted data or irregular data. This step is handled by using Mimics Medical Graphics Software. Next step is conversion of geometric model to a flow model including the crucial preprocessing operation using TGrid which is a commercial preprocessing program. Further, computational grid generation methods are applied to enhance the flow model. In addition to that, for future work it is made possible to add more bifurcations on the computational model. Exporting the geometrical data into a well-known fluid solver (Fluent) requires certain group of simulations and analysis. Therefore, a source mesh file is created for initial simulations that include 3D steady, unsteady (transient) flows with upstream velocities in constant and sinus wave form. All cases are compared according to pressure, shear stress and velocity values.