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Early turbulence and pulsatile flows enhance diodicity of Tesla's macrofluidic valve.

ABSTRACT: Microfluidics has enabled a revolution in the manipulation of small volumes of fluids. Controlling flows at larger scales and faster rates, or macrofluidics, has broad applications but involves the unique complexities of inertial flow physics. We show how such effects are exploited in a device proposed by Nikola Tesla that acts as a diode or valve whose asymmetric internal geometry leads to direction-dependent fluidic resistance. Systematic tests for steady forcing conditions reveal that diodicity turns on abruptly at Reynolds number [Formula: see text] and is accompanied by nonlinear pressure-flux scaling and flow instabilities, suggesting a laminar-to-turbulent transition that is triggered at unusually low [Formula: see text]. To assess performance for unsteady forcing, we devise a circuit that functions as an AC-to-DC converter, rectifier, or pump in which diodes transform imposed oscillations into directed flow. Our results confirm Tesla's conjecture that diodic performance is boosted for pulsatile flows. The connections between diodicity, early turbulence and pulsatility uncovered here can inform applications in fluidic mixing and pumping.

SUBMITTER: Nguyen QM

PROVIDER: S-EPMC8128925 | biostudies-literature | 2021 May

REPOSITORIES: biostudies-literature

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Early turbulence and pulsatile flows enhance diodicity of Tesla's macrofluidic valve.

Nguyen Quynh M QM Abouezzi Joanna J Ristroph Leif L

Nature communications 20210517 1

Microfluidics has enabled a revolution in the manipulation of small volumes of fluids. Controlling flows at larger scales and faster rates, or macrofluidics, has broad applications but involves the unique complexities of inertial flow physics. We show how such effects are exploited in a device proposed by Nikola Tesla that acts as a diode or valve whose asymmetric internal geometry leads to direction-dependent fluidic resistance. Systematic tests for steady forcing conditions reveal that diodici ...[more]

PMID: 34001882

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Project description:BackgroundThis study aimed at assessment of post-transcatheter aortic valve (TAV) replacement hemodynamics and turbulence when a same-size SAPIEN 3 (Edwards Lifesciences Corp, Irvine, Calif) and Medtronic Evolut (Minneapolis, Minn) were implanted in a rigid aortic root with physiological dimensions and in a representative root with calcific leaflets obtained from patient computed tomography scans.MethodsTAV hemodynamics were studied by placing a SAPIEN 3 26-mm and an Evolut 26-mm in rigid aortic roots and representative root with calcific leaflets under physiological conditions. Hemodynamics were assessed using high-fidelity particle image velocimetry and high-speed imaging. Transvalvular pressure gradients (PGs), pinwheeling indices, and Reynolds shear stress (RSS) were calculated.Results(1) PGs obtained with the Evolut and the SAPIEN 3 were comparable among the different models (10.5 ± 0.15 mm Hg vs 7.76 ± 0.083 mm Hg in the rigid model along with 13.9 ± 0.19 mm Hg vs 5.0 ± 0.09 mm Hg in representative root with calcific leaflets obtained from patient computed tomography scans respectively); (2) more pinwheeling was found in the SAPIEN 3 than the Evolut (0.231 ± 0.057 vs 0.201 ± 0.05 in the representative root with calcific leaflets and 0.366 ± 0.067 vs 0.122 ± 0.045 in the rigid model); (3) higher rates of RSS were found in the Evolut (161.27 ± 3.45 vs 122.84 ± 1.76 Pa in representative root with calcific leaflets and 337.22 ± 7.05 vs 157.91 ± 1.80 Pa in rigid models). More lateral fluctuations were found in representative root with calcific leaflets.Conclusions(1) Comparable PGs were found among the TAVs in different models; (2) pinwheeling indices were found to be different between both TAVs; (3) turbulence patterns among both TAVs translated according to RSS were different. Rigid aortic models yield more conservative estimates of turbulence; (4) both TAVs exhibit peak maximal RSS that exceeds platelet activation 100 Pa threshold limit.

Dataset Information

Early turbulence and pulsatile flows enhance diodicity of Tesla's macrofluidic valve.

Publications

Early turbulence and pulsatile flows enhance diodicity of Tesla's macrofluidic valve.

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