As the name suggests, aneurysms located in the thoracic part of the human aorta are called thoracic aneurysms. These aneurysms have very complex anatomies due to brachiocephalic, left common carotid, and left subclavian arterial branches. Hence, stent-grafts that are used to treat thoracic aneurysms must have branches to ensure that the blood flow to these critical arteries is not interrupted after the surgery. As the blood flow in thoracic aortic aneurysms is highly irregular, with flow recirculation zones and vortices, insertion of a branched stent-graft may further increase the complexity of the flow lead to future complications such as thrombosis. Such post-surgical scenarios can be simulated effectively using FSI simulations to gain an insight into the most likely outcome of an operation. Furthermore, within the FSI model, Navier-Stokes equations that govern the blood flow can easily be coupled with the advection-diffusion equations, which can be used to model the blood coagulation cascade, leading to thrombosis. Not only that, once the flow and the pressure field has been quantified through FSI simulations, the displacement forces acting on the stent-graft, which are responsible for the device migration, can be calculated using the technique proposed by Kandail et al. (2014). The magnitude and direction of such displacement forces can give physicians accurate insight if the device will migrate under the hemodynamic loads or not.