Coupled CFD-PBE Predictions of Renal Stone Size Distributions in the Nephron In Microgravity



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46th International Conference on Environmental Systems


In this paper, a deterministic model is developed to assess the risk of critical renal stone formation for astronauts during space travel. A Population Balance Equation (PBE) model is used to compute the change in size distribution of a population of nucleating, growing and agglomerating renal calculi as they are transported through different sections of the nephron. The PBE model is coupled to a Computational Fluid Dynamics (CFD) model that solves for flow of urine and transport of renal calculi along with the ionic species, calcium and oxalate, in the nephron using a Eulerian two-phase mathematical framework. Parametric simulation are performed to study stone size enhancement and steady state volume fraction distributions in the four main sections of the nephron under weightlessness conditions. Contribution of agglomeration to the stone size distribution and effect of wall friction on the stone volume fraction distributions are carefully examined. Simulations using measured astronaut urinary calcium and oxalate concentrations in microgravity as input indicate that under nominal conditions the largest stone sizes developed in Space will be considerably below the critical range for problematic stone development. However, results also indicate that the highest stone volume fraction occurs next to the tubule and duct walls. Thus there is an increased propensity for wall adhesion and possible evolution towards critical sizes.


United States
Utah State University
NASA Glenn Research Center
ICES513: Computational Modeling for Human Health and Performance Analysis
Vienna, Austria
David Thompson, NASA Glenn Research Center, USA
Elise Griffin, NASA Glenn Research Center, USA
The 46th International Conference on Environmental Systems was held in Vienna, Austria, USA on 10 July 2016 through 14 July 2016.
Mohammad Kassemi, NASA Glenn Research Center, USA


Renal Stone, Microgravity, Multiphase Flow, Agglomeration, Nephron