This thesis project aims to develop a two-dimensional CFD model for the study of flows within artificial kidney during Continuous Renal Replacement Therapy (CRRT), a life-saving therapy used in intensive care on patients who have acute renal failure. The study of the equations governing transport through the porous membrane has enabled to describe the behaviour of the fluid both at the interface and within the fiber itself. The model includes simplified assumptions, such as laminar flow, Newtonian fluid behaviour and stationary motion, to make the simulation more manageable, with parameters based on the specifications of the Baxter HF1000 filter. The simulation process on ANSYS was divided into several steps: creation of geometry, generation of mesh, configuration of conditions, resolution and analysis of results.