Biomimetics
Behzad Seyfi; Hosein Mansourinejad; Bahman Vahidi; Nasser Fatouraee
Volume 6, Issue 3 , June 2012, , Pages 169-175
Abstract
Peristaltic flow is one of the important mechanisms of fluid transmission. In addition to the divers engineering applications, this mechanism plays an important role in biological organs such as digestion system and urine excretion. In this paper, urine bolus transportation in ureter has been investigated ...
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Peristaltic flow is one of the important mechanisms of fluid transmission. In addition to the divers engineering applications, this mechanism plays an important role in biological organs such as digestion system and urine excretion. In this paper, urine bolus transportation in ureter has been investigated experimentally using a peristaltic flow simulator apparatus. Some of the features of this apparatus worth mentioning are its ability to use it to investigate the influence of some important parameters in peristaltic flow, such as the effect of pressure difference between the kidney and the bladder on the quantity of discharge and reflux rates, effect of the mean velocity of bolus transport on discharge rate, existence of fluid film and its effect on bolus discharge rate, and effect of fluid bolus length on reflux rate. Then we compare the obtained results with the similar theoretical studies. It was observed that an increase in the pressure difference between inlet and outlet decreases the ratio of reflux to initial volume of the bolus, and it increases the discharge rate. Moreover, the quantities of reflux and discharge rate decrease by decreasing the bolus transport velocity. It was also observed that the thickness of the fluid film has an inverse relation with respect to the discharge rate and with increasing the bolus length reflux is increasing.
Fluid-Structure Interaction in Biological Media / FSI
Bahman Vahidi; Nasser Fatouraee; Ali Imanparast
Volume 2, Issue 1 , June 2008, , Pages 29-37
Abstract
Ureter reflux is one of the prevalent factors that causes pyelonefrit and sistit syndromes. Dilatation of ureter, renal pelves and calyx are detectable with reflux. In this paper, in order to analyze this phenomenon, an axisymmetric model was introduced. We utilized a rigid body, which is in contact ...
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Ureter reflux is one of the prevalent factors that causes pyelonefrit and sistit syndromes. Dilatation of ureter, renal pelves and calyx are detectable with reflux. In this paper, in order to analyze this phenomenon, an axisymmetric model was introduced. We utilized a rigid body, which is in contact with the outer ureter wall to model ureter contraction. The Navier-Stokes equations are solved for the fluid and a linear elastic model is used for ureter wall structure. The finite element equations for both the structure and the fluid were solved by the Newton-Raphson iterative method. The effect of ureter wall elasticity, pressure difference between the ureter inlet and outlet and the effect of the average velocity of peristaltic wave along the length of the ureter on the ureter outlet flow rate were analyzed. Moreover, the effect of the number of contraction waves on the pressure and flow relations in the ureter was analyzed. Increase in the number of contraction waves reduced the flow passing through the ureter. The results of investigating about the contraction wave velocity variations indicated that if average velocity the contraction wave was lower than a limited magnitude, its existence did not have any considerable effect on the ureter outlet flow rate. Finally improper function of urinary tubes junctions results in the passage of a part of back flow even in the case of low velocity beginning of the contraction wave.
