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호흡량에 따른 사람의 기도 내 유동 특성에 관한 수치 해석적 연구
성건혁(K.H. Sung),노경철(K.C. Ro),유홍선(H.S. Ryou) 한국전산유체공학회 2012 한국전산유체공학회 학술대회논문집 Vol.2012 No.5
The inspiratory rate of a human is changed with the amount of the workload. The flow field is affected by the inspiratory flow rate. In the flow filed, the wall shear stress is important to predict the inflammation or a injury in airway wall. In addition, the turbulence intensity and secondary flow affect the deposition pattern of particle which is important for the drug-aerosol targeting. Thus the analysis of the flow characteristic in a human airway is important. The purpose of this study is to investigate the effects of the inspiratory flow rate on the flow characteristics in a human airway. The tubular airway is consistent with the oral cavity, pharynx, larynx and trachea. The constant inspiratory flow rate is used at each case of human states regarding the workload. By the effect of geometric airway changes, transition to turbulent airflow after the larynx can occur with relaminarization further downstream. Consequently, the low Reynolds number k-ω turbulence model is used for analysis with flow regime. As the inspiratory flow rate is larger, the wall shear stress and the turbulence intensity increase in airway. On the other hand, the area of recirculation zone is smaller.
혈액 투석시 충혈방법에 따른 인조혈관 내 유동 특성에 관한 수치해석 연구
김지태(J.T. Kim),성건혁(K.H. Sung),유홍선(H.S. Ryou) 한국전산유체공학회 2013 한국전산유체공학회지 Vol.18 No.3
Renal failure patients have to operate arteriovenous graft for hemodialysis. Blood flow characteristics influence the patency rate of arteriovenous graft. Numerical investigation is performed with the arteriovenous graft according to injection of blood. As a result, when the injection is not applied to venous graft, the low wall shear stress region appears at venous anastomosis. It may cause intimal hyperplasia at venous anastomosis.
혈액 출입에 따른 투석용 인조혈관 내 유동 특성에 관한 수치해석 연구
김소윤(S.Y. Kim),성건혁(K.H. Sung),유홍선(H.S. Ryou),김향경(H.K. Kim) 한국전산유체공학회 2012 한국전산유체공학회 학술대회논문집 Vol.2012 No.11
Hemodialysis is a widely used renal replacement method for patients with renal failure. It is important to improve the patency rate of the vascular access for efficient dialysis. Hemodynamics in the access should be considered to achieve a high patency rate since complications such as an intimal hyperplasia are associated with the flow pattern. In this study, a numerical analysis is performed on the effect of aspirate and return of the blood. High averaged wall shear stress and circulation flow occurs around the anastomosis of artery irrespective of the hemodialysis. Thrombus can be initiated at the bifurcation of the anastomosis. Low shear zone and high oscillatory shear index also appear at the venous anastomosis when the blood is return through the venous catheter. Therefore, the return of blood can be one of the reasons of complications in the venous anastomosis.
비뉴턴 특성을 고려한 혈액투석용 인조혈관 내 카데터 각도에 따른 혈류유동에 관한 수치해석 연구
김소윤(S.Y. Kim),성건혁(K.H. Sung),유홍선(H.S. Ryou) 한국전산유체공학회 2012 한국전산유체공학회 학술대회논문집 Vol.2012 No.5
For patients with renal failure, the renal replacement therapies are needed. Hemodialysis is widely used renal replacement method to remove the waste products. It is important to improve a patency rate of the vascular access for efficient dialysis. Since some complications are associated with the flow pattern, considering hemodynamics in the access is needed for high patency rate. Also, blood flow from an artificial kidney affects the flow in the access. Therefore, technique of hemodialysis such as a catheter angle or dialysis dose have to be set up, but there is no standard clearly. In this study, the numerical analysis is performed for an effect of the catheter angle on the flow in the graft. Blood is assumed to be a non-Newtonian fluid. For the smaller angle than 5°, there is lower AWSS and high OSI region appears because of the circulation zone at the venous graft. With the catheter angle of 15~20°, high AWSS at the bottom of the venous graft occurs and there is high OSI zone locally. It can be suggested that the catheter angle around 10° is appropriate to minimize the stenosis or thrombus.