A Mathematical Simulation of the Ureter: Effects of the Model Parameters on Ureteral Pressure/Flow Relations
- 4 February 2011
- journal article
- Published by ASME International in Journal of Biomechanical Engineering
- Vol. 133 (3), 031004
- https://doi.org/10.1115/1.4003316
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.Keywords
This publication has 25 references indexed in Scilit:
- Discs-large homolog 1 regulates smooth muscle orientation in the mouse ureterProceedings of the National Academy of Sciences of the United States of America, 2006
- Mathematical models in urinary system mechanics (review)Fluid Dynamics, 2005
- Normal Ureter Size on Unenhanced Helical CTAmerican Journal of Roentgenology, 2004
- The role of PAX2 in normal and abnormal development of the urinary tract.Pediatric Nephrology, 1998
- Neuroprotective Activity of Fructose-1,6-Bisphosphate Following Transient Forebrain Ischemia in the Mongolian GerbilThe Japanese Journal of Pharmacology, 1993
- Dynamics of the upper urinary tract: II. The effect of variations of peristaltic frequency and bladder pressure on pyeloureteral pressure/flow relationsPhysics in Medicine & Biology, 1987
- Pathogenetic factors in vesicoureteral refluxNeurourology and Urodynamics, 1986
- Changes in the ureteral peristaltic rate and the bolus volume in gradual and rapid urinary frow increase.The Tohoku Journal of Experimental Medicine, 1985
- The ureteral lumen during peristalsisJournal of Anatomy, 1972
- DEMONSTRATION OF "GAP JUNCTIONS" BETWEEN SMOOTH MUSCLE CELLSThe Journal of cell biology, 1970