Three-dimensional simulation of urine flow in the male lower urinary tract: A modified computational fluid dynamic study

Computational modeling of urine flow is emerging as a novel method for investigating the mechanical properties of the male lower urinary tract and simulating pathological conditions. Such models offer the potential to obviate invasive diagnostic methods, such as urethroscopy, by analyzing urine spray behavior to locate pathological strictures instead of direct visualization of the tract interior. However, current computational models fail to simulate the anatomy and dynamic properties of the male lower urinary tract accurately. We devised a modified three-dimensional (3D) computational model of the normal male lower urinary tract using a more detailed anatomical approach than that used in previous studies.

An idealized 3D geometry representing the male lower urinary tract system was constructed using COMSOL v4.2. Specific geometric parameters were defined for each component from the bladder to the external urethral orifice. After applying the preconditions used for computational fluid dynamics studies of the urinary tract, urine flow characteristics were studied using an idealized 3D model.

Urine velocity reached its maximum in the membranous urethra in the variable-diameter model, near the transition into the bulbous urethra, and declined toward the urethral orifice. We demonstrated the vortical flow pattern in the prostatic and membranous urethra, in addition to the normal streamlined flow. The urethral pressure field profile showed that the gradient was not uniform in the urethra and varied as urine flowed.

Computational fluid dynamics models in urology are a growing area of interest that requires further refinement for translation into a validated diagnostic method. This study provided an updated framework for developing future computational fluid dynamics studies on the male lower urinary tract.