Biomech Model Mechanobiol DOI 10.1007/s10237-017-0898-2 ORIGINAL PAPER Numerical and experimental analysis of the transitional flow across a real stenosis R. Agujetas 1 · C. Ferrera 1 · A. C. Marcos 2 · J. P. Alejo 3 · J. M. Montanero 1 Received: 2 December 2016 / Accepted: 15 March 2017 © Springer-Verlag Berlin Heidelberg 2017 Abstract In this paper, we present a numerical study of the pulsatile transitional flow crossing a severe real steno- sis located right in front of the bifurcation between the right subclavian and right common carotid arteries. The sim- ulation allows one to determine relevant features of this subject-specific flow, such as the pressure waves in the right subclavian and right common carotid arteries. We explain the subclavian steal syndrome suffered by the patient in terms of the drastic pressure drop in the right subclavian artery. This pressure drop is caused by both the diverging part of the ana- lyzed stenosis and the reverse flow in the bifurcation induced by another stenosis in the right internal carotid artery. Keywords CFD · Stenosis · Subclavian steal syndrome 1 Introduction Atherosclerosis is the artery hardening and thickening caused by the growth of atheromatous plaques in the intima or endothelium (Ibañez et al. 2009; Kleinstreuer 2006). It is the first cause of disability and death in the developing world (Murray and Lopez 2013). Atherosclerosis can cause coro- nary heart disease, ischemic stroke, and peripheral vascular disease when obstructing blood flow to the heart, brain, B J. M. Montanero jmm@unex.es 1 Depto. de Ingeniería Mecánica, Energética y de los Materiales and Instituto de Computación Científica Avanzada (ICCAEx), Universidad de Extremadura, 06006 Badajoz, Spain 2 Depto. de Expresión Gráfica, Universidad de Extremadura, 06006 Badajoz, Spain 3 Servicio de Radiología, Hospital Infanta Cristina, 06006 Badajoz, Spain or lower extremities, respectively (Bentzon et al. 2014). There is accumulating evidence that hemodynamics influ- ences anomalous cellular development on arterial walls (such as atherosclerosis) and vice versa. For instance, it is well known that atherosclerotic lesions occur predominantly at regions of low and oscillatory wall shear stresses (WSS). Those lesions in turn alter the velocity field causing flow separation, secondary flows, and flow blockage among other effects. They also affect the flow resistance, mixing rates, or platelet coagulation rates (Bluestein et al. 1999; Stroud et al. 2000). Computational fluid dynamics (CFD) has proved to be a reliable tool for modeling arterial blood flow (Ku 1997), and more specifically the circulation across stenoses. The sim- ulation results may be especially significant in treating this pathology because clinical decisions are not always based on the necessary hemodynamic information. In fact, the crite- ria to operate on asymptomatic stenoses are far from being well established (David-Spence and Ross-Naylor 2016). In this paper, we present a numerical study of the pulsatile tran- sitional flow crossing a severe real stenosis and show how the CFD results explain the symdrome experienced by the patient. CFD has been frequently used to analyze idealized steno- sis geometries (see, e.g., Ghalichi et al. (1998); Varghese and Frankel (2003); Lee et al. (2003); Ryval et al. (2004); Varghese et al. (2007a, b); Tan et al. (2011); Caballero and Laín (2013); Sommer et al. (2015)). Although relevant infor- mation can be extracted from these simulations, realistic models are required to get results applicable to clinical sit- uations. For this reason, idealized shapes are giving way to patient-specific geometries reconstructed from medical imaging techniques, such as magnetic resonance (MR). In this case, one of the major problems is the reconstruction of the intricate local anatomy delimiting the fluid domain, which 123