Out of the 100,000 patients currently on the wait list for a life-saving organ transplant, only one third will receive the organ that they need within a year. The low number of transplantations is not caused by a lack of donated organs, but rather a lack of technology capable of preserving organs for extended periods of time. The gold standard of organ preservation is static hypothermic storage, which only preserves an organ for a few hours. Fortunately, multiple organ preservation devices that incorporate both hypothermic storage and pulsatile perfusion have been developed. The pulsatile perfusion in those devices is commonly regulated by an electronically-powered switching component. Unfortunately, those components can add significant complications to the device, such as cyclical fatigue, mechanical and electrical failure, and power requirements. We have developed an innovative fluidic oscillator with no moving parts (FONMP) as a means to mitigate the drawbacks associated with electronically-controlled operation. 

In order to optimize a FONMP for use within an organ preservation device, reliable computational fluid dynamic (CFD) simulations with an accurate turbulence model were necessary. In order to validate accuracy of a turbulence model, an experimentally studied FONMP was selected and simulated using OpenFOAM. The previously studied FONMP was modeled using the computer-aided design (CAD) software Onshape. Three tetrahedral meshes (of varying qualities) were created using ANSYS Meshing software. Air was used as the working fluid and various mass flow rates (6 – 24 g/s) were evaluated. The kinematic viscosity of air was set to 1.5e-5 m^2^/s and the air was considered incompressible due to the maximum calculated velocity being approximately 35 m/s (M ≈ 0.1). A no-slip velocity function was set for all walls. Each of the three meshes was evaluated with seven different Reynolds-Averaged Simulation (RAS) turbulence models: k-ε, Re-Normalization Group (RNG)-k-ε, k-ω, k-k~L~-ω, k-ω-Shear Stress Transport (SST), k-ω-SST-Langtry-Manter (LM), and k-ω-SST-Scale Adaptive Simulation (SAS). The initial turbulent kinetic energy (k), initial rate of dissipation of turbulent energy (ε), and specific rate of dissipation of turbulent kinetic energy (ω) were calculated for each case.

The k-ω-SST-SAS turbulence model produced the most accurate results across all mesh sizes. The OpenFOAM simulations that utilized the k-ω-SST-SAS turbulence model produced oscillation frequencies (created by various mass flow rates) with an average accuracy of 9.1%. As expected, meshes of higher qualities produced more accurate results. Future work will utilize this turbulence model to evaluate oxygen moving through FONMPs. Additional FONMP designs will also be evaluated, and their geometries and dimensions will be altered to produce the necessary oscillation frequencies and mass flow rates requited by organ preservation devices.


Optimizing a Fluidic Oscillator for Organ Preservation

Division / Sponsors: 
Heat Transfer Division (HTD), Fluids Engineering Division (FED)

Heat Transfer Summer Conference
Paper Proceedings: https://asmedigitalcollection.asme.org/HT/HT2020/volume/83709

18th International Conference on Nanochannels, Microchannels, and Minichannels
Paper Proceedings: https://asmedigitalcollection.asme.org/ICNMM/ICNMM2020/volume/83693

Fluids Engineering Division Summer Meeting
Paper Proceedings: https://asmedigitalcollection.asme.org/FEDSM/FEDSM2020/volume/83716

HT-ICNMM2020 - Virtual Conference, SHTC - Virtual Conference, FEDSM2020 - Virtual Conference

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