INVESTIGATION OF VASCULAR FLOW IN A THORACIC AORTA IN TERMS OF FLOW MODELS AND BLOOD RHEOLOGY VIA COMPUTATIONAL FLUID DYNAMICS (CFD).

The studies on vascular flows have increased in the last decade. In this work; we have focused on the effects of flow model and blood rheology on hemodynamics for a real-subject scan using Computed Tomography Angiography (CTA) during numerical solutions. Various vascular flow studies using Newtonian or non-Newtonian blood models were presented in the literature with laminar or turbulent flow assumptions. In this study; six different turbulent models (Realizable k- ε , Standard k- ε , SST k- ω , Standard k- ω , Transition k-kl- ω , Transition SST) were compared to laminar flow to show whether turbulent flow solution is necessary. Blood rheology was investigated by using five different non-Newtonian models (Carreau, Herschel–Bulkley, Carreau–Yasuda, Casson, Power-Law) in addition to Newtonian model to indicate whether non-Newtonian blood assumptions is necessary. The In vivo boundary conditions were utilized by the UDF code which defines the real-patient cardiac cycle obtained by Echocardiography (ECHO) to present hemodynamics in the study. The results show that laminar flow well matched with the four turbulent models and two models shows by 4.8% and 19.5% differences in Wall Shear Stress (WSS) according to laminar flow. When the blood rheology was investigated, results revealed significant differences in WSS by 25.7%, 8.7%, 22.4%, 12.3%, and 32.5% for the non-Newtonian models in the given order, respectively, compared to Newtonian assumption. It concluded that laminar flow solution could be effective instead of solving turbulent flows in terms of computational cost, however, non-Newtonian blood effects could be considered to determine critical hemodynamics levels in a normal aortic arc. [ABSTRACT FROM AUTHOR]