Abstract
This study aims to characterize the effect of inflow pulsatility on the hydrodynamic power loss inside intersecting double-inlet, double-outlet pipe intersection (DIPI) with cross-flow mixing. An extensive set of computational fluid dynamics (CFD) simulations was performed in order to identify the individual effects of flow pulsatility parameters, i.e., amplitude, frequency, and relative phase shift between the inflow waveform oscillations, on power loss. An experimentally validated second order accurate solver is employed in this study. To predict the pulsatile flow performance of any given arbitrary inflow waveforms, we proposed three easy-to-calculate pulsatility indices. The frequency-coupled quasi-steady flow theory is incorporated to identify the functional form of pulsatile power loss as a function of these indices. Our results indicated that the power loss within the inflow branch sections, lumped outflow-junction section, and the whole conduit correlates strongly with the pulsatility of each inflow waveform, the total inflow pulsatility, and inflow frequency content, respectively. The complete CFD simulation matrix provided a unified analytical expression that predicts pulsatile power loss inside a one-degree offset DIPI geometry. The predictive accuracy of this expression is evaluated in comparison to the CFD evaluation of arbitrary multi-harmonic inflow waveforms. These results have important implications on hydrodynamic pipe networks that employ complex junctions as well as in the patient-to-patient comparison of surgically created vascular connections. Coupling the present analytical pulsatile power loss expression with non-dimensional steady power loss formulation provided a valuable predictive tool to estimate the pulsatile energy dissipation for any arbitrary junction geometry with minimum use of the costly CFD computations.
Highlights
Cross-flow jet flows, where two jet wakes from opposed nozzles impinge, are widely used in industrial applications, such as polymer processing,1 nanoparticle synthesis,2 and stream reactors,3–7 to enhance fluid mixing efficiency and combustion
The parametric analytical formulation pioneered in this study introduced easy-to-calculate pulsatility indices that correlate with the pulsatile energy efficiency of double inlet pipe intersection (DIPI) geometry with limited cross-flow mixing
Our results indicate that the power loss within the inflow branches, the lumped outflow-junction section, and the whole conduit correlates strongly with the pulsatility of each inflow waveform (IPI, p < 0.05), the total inflow pulsatility (TIPI, p < 0.05), and the inflow frequency content (IFI, p < 0.05), respectively
Summary
Cross-flow jet flows, where two jet wakes from opposed nozzles impinge, are widely used in industrial applications, such as polymer processing, nanoparticle synthesis, and stream reactors, to enhance fluid mixing efficiency and combustion. Associated hydraulic energy dissipation has been studied extensively in relation to traditional junctions with simple topologies that are used as a core application of fluid dynamics in underground pipe networks, liquid distribution lines, and branching networks, where the optimum system efficiency requires improved internal flow conditions and optimal hydrodynamic design at these pipe intersections. The local flow dynamics of this junction have been extensively studied in order to minimize energy dissipation within the connection, which relieves the elevated post-operative systemic resistance and improves the efficiency of the single ventricle circuit.. Dynamic instabilities and oscillatory behavior within the junction zone have been well documented for the opposed-jet flows under the laminar inlet flow regime, and the introduction of an offset between the inflow branches has demonstrated higher stability and lower energy dissipation.. Patients with univentricular heart defects require a series of palliative surgical operations, such as the Fontan procedure, which involves the use of opposed-jet vascular connections for total cavopulmonary connection (TCPC). The local flow dynamics of this junction have been extensively studied in order to minimize energy dissipation within the connection, which relieves the elevated post-operative systemic resistance and improves the efficiency of the single ventricle circuit. Dynamic instabilities and oscillatory behavior within the junction zone have been well documented for the opposed-jet flows under the laminar inlet flow regime, and the introduction of an offset between the inflow branches has demonstrated higher stability and lower energy dissipation.
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