Fluid structure interaction in abdominal aortic aneurysm using ANSYS Workbench by Florentina Ene Outline • Objectives • Abdominal aortic aneurysm (AAA) • Computational methods (CM)  Finite Element Analysis (FEA)  Computational Fluid Dynamics (CFD)  Fluid Structure Interaction (FSI) • Validation of CM • Comparison of CM • Haemodynamics and mechanical factors Objectives • To simulate the interaction between the blood flow and the diseased aneurismal wall by – Computational simulation – Experimental testing for the study of abdominal aortic aneurysm (AAA) • To investigate the influence of certain haemodynamics factors Abdominal Aortic Aneurysm (AAA) • AAA - a localised abnormal dilatation of the abdominal aorta • Diameter - 1.5 times larger than the nominal diameter • Causes - primarily atherosclerosis • Population - 4:1 ratio male to female, 75% over 60 years old • Risk - a high risk of sudden rupture • Rupture - 3:1 female to male risk rupture http://www.emedicine.com/MED Physics of AAA • Rupture of AAA – Surgical criterion: max diameter 5-5.5 cm – Maximum wall stress (Raghavan, 1996) – Asymmetry influence (Vorp, 1998; Scotti,2005) – Intraluminal thrombus (ILT) (Wang, 2002) – Pulsating interaction (DiMartino, 2001) Hemodynamics in AAA • Low flow • Recirculation regions • Secondary flow • Low mean wall shear stress • Temporal oscillations in shear (Moore,1992; Moore, 1994; Taylor,1998; Taylor, 2002; Long,1998; Tang, 2006) ANSYS Workbench • ANSYS Workbench – ANSYS ICEM  Mesh – ANSYS Simulation (ANSYS Structural)  FEA – ANSYS CFX  CFD Computational Methods for AAA • Structural Pressure Analysis (FEA) – Static (sFEA) – Transient (tFEA) • Computational Fluid Dynamics (CFD) – Steady flow (sCFD) – Pulsating flow (tCFD) • Fluid-Structure Interaction (FSI) – Steady FSI (sFSI) – Pulsating FSI (tFSI) Computational Methods for AAA • FEA evaluates rupture potential – Deformations – Stresses • CFD evaluates unfavourable flow conditions – Velocity distribution – Pressure distribution – Wall shear stress • FSI evaluates rupture potential due to extra loading of unfavourable flow conditions Steps of Computational Methods • Geometry • Mesh (Elements) 1 Pre-processor • Materials • Boundary conditions • Convergence Solver 2 • Solution monitor and control • Independence analysis 3 Post-processor • Validation • Comparison