Fluid structure interaction in abdominal aortic aneurysm - cadfem

38 Pages·2011·1 MB·English

by  Ene, Florentina

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