BIOMEDICAL ENGINEERING- APPLICATIONS, BASIS & COMMUNICATIONS PULSATILE FLOW FIELDS IN A MODEL OF ABDOMINAL AORTA WITH ITS PERIPHERAL BRANCHES D. LEE, J. Y. CHEN Institute of Aeronautics and Astronautics National Cheng Kung University Tainan, Taiwan ABSTRACT In a previous study by the authors, steady flow fields in a model of abdominal aorta with its seven peripheral branches were reported. In the present study, the some aorta model was simulated numerically with a pulsatile inlet waves for both the resting and exercise conditions. The baseline pulsatile flow field was presented in terms of velocity vectors and iso-velocity contours as well as the wall shear stress (WSS) distribution and the recirculation zones. The time-averaged behavior of the flow field represented by the fluid dynamic factors was discussed. The results were consistent with those obtained experimentally and numerically by other investigators. It was also found that under the present conditions, the steady flow behavior could adequately describe the time-averaged behavior of its corresponding pulsatile case, particularly in the regions where convective flow dominated. The present computer code may provide a platform for clinical simulations. Biomed Eng Appi Basis Comm, 2003 (October); 15: 170-178. Keywords: abdominal aorta, wall shear stress, reversed flows 1. INTRODUCTION The upstream part of the abdominal aorta comes from a relatively straight descending thoracic aorta and branches into two renal arteries and into the celiac trunk. Significant portion of the blood from the thoracic aorta flows into the renal arteries and about one third of the blood passes into the legs under the rest condition. Interestingly, atherosclerotic disease extends along the posterior wall of the relatively straight abdominal aorta downstream of the renal arteries in all people and rarely is found in the Received: Aug 4, 2003; Accepted: Oct 1, 2003 Correspondence: Denz Lee, Professor Institute of Aeronautics and Astronautics National Cheng Kung University, Tainan, Taiwan 701 E-Mail: [email protected] 170 upstream thoracic aorta [1]. To explain this, thorough understanding of the flow fields resulted from the peripheral branches should be of importance. Recently, flow fields of four branches (i.e. two renals and two iliacs, [2]) and flow fields in a tube with two branches [3] were studied. Flow fields in a more complete model were studied experimentally [4-9]. Numerically, Taylor et al. [ 10-11 ] employed a finite element method (FEM) in modeling three-dimensional pulsatile flows in the abdominal aorta. Many biomedical fluid dynamic studies have been focused on flow behavior and wall shear stress in aorta. Clinical observations show that plaques occurred preferentially in zones where the flow is locally disturbed and extreme wall shear stresses appear[1,9]. In addition to geometry, there are quite a few other factors which also significantly affect the flow pattern [5-7, 12-14]. Among them are the flow rate (Reynolds number), branching ratio, unsteadiness (waveform) and - 1 - Biomed. Eng. Appl. Basis Commun. 2003.15:170-178. Downloaded from www.worldscientific.com by 14.185.88.171 on 07/11/23. Re-use and distribution is strictly not permitted, except for Open Access articles.
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