Understanding the dynamics of aortic blood flow plays a vital role for the assessment of cardiovascular health for identifying potential risk factors for diseases like aneurysm, thrombosis etc. Fluid structure interaction (FSI) can be used to study the aortic blood flow and how this is affected by the mechanical properties of the aortic wall, such as its stiffness and compliance. The results of FSI simulations can provide insight into the factors that contribute to aortic blood flow patterns and predict failures which might be the reason for cardiovascular diseases. The FSI problem of blood flow in aortic aneurysm is solved on an unstructured grid based on partitioned approach using opensource softwares; Openfoam (CFD) [1] and CalculiX (CSM) [2] coupled using preCICE coupling tool[3]. The flow is assumed to be laminar and isotropic linear elastic model of CalculiX is used for the arterial wall computations. In this work an idealized geometry representing aneurysmatic blood vessel is created and FSI study is performed. The non-matching mesh interface of fluid and solid is handled by data-mapping methods of preCICE. Unsteady flow phenomena representing the systolic and diastolic phase of heart is simulated and the hemodynamic indices such as the wall shear stress (WSS), time averaged WSS (TAWSS), Oscillatory Shear Index (OSI) are quantified from the simulation data. The OSI and TAWSS metrics are used to identify the rupture prone regions within the aneurysm [4]. These indices are compared between the CFD with rigid walls and FSI studies to quantify the differences. The mesh-sensitivity analysis is performed by generating different resolutions of mesh for fluid and solid domains.