Abstract In the past years multiphysics computational models aiming at describing clot formation and growth have been developed using different constitutive equations. Most models were designed to investigate the interactions between many agents of the so-called coagulation cascade but were based on simple assumptions to describe the complex interaction between the clot and the flow. The models integrating the more elaborate Phan-Thien-Tanner (PTT) model, able to describe the viscoelastic behavior of the clot, have been successfully implemented to simple geometries but seem to be difficult to control when applied to complex ones. In aneurysm clot modeling, where complex geometry and sophisticated viscoelastic models are essential to realistic simulation outcomes, its successful implementation appears as a necessity. The paper presented here focused on a stabilization strategy to circumvent the numerical difficulties when applying the PTT-model to a more complex aneurysm geometry with implanted flow diverter.