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A Mathematical Simulation of the Ureter: Effects of the Model Parameters on Ureteral Pressure/Flow Relations

Vahidi, Bahman and Fatouraee, Nasser and Imanparast, Ali and Moghadam, Abbas Nasiraei (2011) A Mathematical Simulation of the Ureter: Effects of the Model Parameters on Ureteral Pressure/Flow Relations. Journal of Biomechanical Engineering, 133 (3). Art. No. 031004. ISSN 0148-0731. https://resolver.caltech.edu/CaltechAUTHORS:20110308-105948430

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Abstract

Ureteral peristaltic mechanism facilitates urine transport from the kidney to the bladder. Numerical analysis of the peristaltic flow in the ureter aims to further our understanding of the reflux phenomenon and other ureteral abnormalities. Fluid-structure interaction (FSI) plays an important role in accuracy of this approach and the arbitrary Lagrangian–Eulerian (ALE) formulation is a strong method to analyze the coupled fluid-structure interaction between the compliant wall and the surrounding fluid. This formulation, however, was not used in previous studies of peristalsis in living organisms. In the present investigation, a numerical simulation is introduced and solved through ALE formulation to perform the ureteral flow and stress analysis. The incompressible Navier–Stokes equations are used as the governing equations for the fluid, and a linear elastic model is utilized for the compliant wall. The wall stimulation is modeled by nonlinear contact analysis using a rigid contact surface since an appropriate model for simulation of ureteral peristalsis needs to contain cell-to-cell wall stimulation. In contrast to previous studies, the wall displacements are not predetermined in the presented model of this finite-length compliant tube, neither the peristalsis needs to be periodic. Moreover, the temporal changes of ureteral wall intraluminal shear stress during peristalsis are included in our study. Iterative computing of two-way coupling is used to solve the governing equations. Two phases of nonperistaltic and peristaltic transport of urine in the ureter are discussed. Results are obtained following an analysis of the effects of the ureteral wall compliance, the pressure difference between the ureteral inlet and outlet, the maximum height of the contraction wave, the contraction wave velocity, and the number of contraction waves on the ureteral outlet flow. The results indicate that the proximal part of the ureter is prone to a higher shear stress during peristalsis compared with its middle and distal parts. It is also shown that the peristalsis is more efficient as the maximum height of the contraction wave increases. Finally, it is concluded that improper function of ureteropelvic junction results in the passage of part of urine back flow even in the case of slow start-up of the peristaltic contraction wave.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1115/1.4003316 DOIUNSPECIFIED
Additional Information:© 2011 ASME. Contributed by the Bioengineering Division of ASME for publication in the Journal of Biomechanical Engineering. Manuscript received April 23, 2010; final manuscript received December 13, 2010; accepted manuscript posted December 22, 2010; published online February 4, 2011. Assoc. Editor: Dalin Tang.
Subject Keywords:biological fluid dynamics, biological tissues, elastic waves, elasticity, iterative methods, kidney, Navier-Stokes equations, peristaltic flow, physiological models, pipe flow
Issue or Number:3
Classification Code:PACS: 87.19.rh; 87.19.rj; 87.19.rd; 47.63.-b; 47.10.ad
Record Number:CaltechAUTHORS:20110308-105948430
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20110308-105948430
Official Citation:A Mathematical Simulation of the Ureter: Effects of the Model Parameters on Ureteral Pressure/Flow Relations Bahman Vahidi, Nasser Fatouraee, Ali Imanparast, and Abbas Nasiraei Moghadam, J. Biomech. Eng. 133, 031004 (2011), DOI:10.1115/1.4003316
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:22709
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:08 Mar 2011 21:37
Last Modified:03 Oct 2019 02:39

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