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# Simulation and optimization of Tesla valves

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## Abstract

Tesla valve is a no-moving parts valve. It has many advantages over conventional check-valves in microscale. However, there has been very few literatures discussing its optimization. We present a comprehensive method to optimize the valve. Complete design optimization parameters of the valve are identified for the first time. A method to construct the geometry of the valve is also proposed. Numerical method is used to study steady flow 2-D models of different valves and to derive formulas for optimum geometrical parameters. The optimum angle alpha and the optimum straight segment L are inversely proportional and proportional to the Reynolds number, respectively. This work allows systematic designing of Tesla valves. Depending on the required flow range, an optimum design can be proposed.
Nanotech 2003, Vol.1, www.nsti.org, ISBN 0-9728422-0-
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Nanotech 2003, Vol.1, www.nsti.org, ISBN 0-9728422-0-
9
Nanotech 2003, Vol.1, www.nsti.org, ISBN 0-9728422-0-
9
Nanotech 2003, Vol.1, www.nsti.org, ISBN 0-9728422-0-
9
... A key and subtle limitation of this simple bubbler design is that the flow of gaseous vapour is not unidirectional which leads to the vapour becoming trapped around the sample reservoir. In this paper, we present a novel bubbler design using Tesla valves [20][21][22] , as shown in FIG. 2, that delivers a gas jet of cis-stilbene molecules with a unidirectional high speed flow, leading to a significantly larger gas density in the interaction region. We demonstrate using a bubbler with Tesla valves an order-of-magnitude increase in the detected stilbene molecular ion signal following the strong-field tunnel ionization (SFTI) 9,23,24 of stilbene molecules in the presence of a 97 fs (FWHM) 3.2 μm laser pulse. ...
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Supersonic jets of gas-phase atoms and small molecules have enabled a variety of ultrafast and ultracold chemical studies. However, extension to larger, more complex neutral molecules proves challenging for two reasons: (i) Complex molecules, such as cis-stilbene, exist in a liquid or solid phase at room temperature and ambient pressure and (ii) a unidirectional flow of high-density gaseous beams of such molecules to the interaction region is required. No delivery system currently exists that can deliver dense enough molecular jets of neutral complex molecules without ionizing or exciting the target for use in gas-phase structural dynamics studies. Here, we present a novel delivery system utilizing Tesla valves, which generates more than an order-of-magnitude denser gaseous beam of molecules compared to a bubbler without Tesla valves at the interaction region by ensuring a fast unidirectional flow of the gaseous sample. We present combined experimental and flow simulations of the Tesla valve setup. Our results open new possibilities of studying large complex neutral molecules in the gas-phase with low vapor pressures in future ultrafast and ultracold studies.
... This work presents systematic experimental characterizations of Nikola Tesla's fluidic valve or diode across a wide range of both steady and unsteady flow conditions. The case of steady pressure/ flow-rate considered in previous studies on Tesla-like channels provides a point of comparison to our results 13,[16][17][18][21][22][23][24]31,34,35,13 . No earlier work reports on the abrupt rise in diodicity, which likely reflects the singular values or narrow ranges in Re explored. ...
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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 $${\rm{Re}}\approx 200$$ Re ≈ 200 and is accompanied by nonlinear pressure-flux scaling and flow instabilities, suggesting a laminar-to-turbulent transition that is triggered at unusually low $${\rm{Re}}$$ Re . 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.
... Due to the Tesla valve's unique design and passive operation, several researchers conducted comprehensive studies aimed to visualize flow patterns and improve the diodicity. To explore steady-state flow pattern for different Tesla valves, Truong and Nguyen [51] have used a numerical approach and also derived formulae for optimum geometric parameters. Later, a two-dimensional CFD optimization study with six independent, non-dimensional geometric design variables was carried out, and results showed a 25% higher diodicity for Reynolds number in the range 0 < Re ≤ 2000 compared to commonly used Tesla valve [52]. ...
Article
Flow instability in supercritical fluid based natural circulation loop (NCL) is still an investigation aspect of physical and mathematical problems to comprehend. Therefore, NCLs require precise design assessment that focuses on the interaction of all the transient responses of buoyancy and friction forces which can ensure a stable zone of operation. To promote the uni-directional circulatory movement of loop fluid and to decrease the magnitude of instability, this research emphasizes the development of NCL integrated with two modified Tesla type valves. In this article, numerical simulations have been carried out for a range of supercritical pressures (80–100 bar) and heat inputs (500–2000 W) to do the comparative investigation of instability phenomenon in supercritical carbon dioxide based regular natural circulation loop and a new modified twin Tesla NCL. Results show that the use of modified Tesla valves leads to better stabilization for all supercritical pressures and heat inputs considered in the study. It is also found that the proposed Tesla NCL mitigates the temperature and velocity oscillations with a marginal drop of ⩽3% in the heat transfer performance. Using asymmetrical flow resistance to stimulate directional circulation is an efficient technique to combat this instability issue. Obtained results are validated with the existing correlations, and a good agreement is obtained.
... Forster et al. [35] carried out both CFD and experimental study to prove the effectiveness of Tesla valve in a micro-pump. Truong and Nguyen [36] have used a numerical approach to explore steadystate flow pattern for different Tesla valves and derived formulae for optimum geometric parameters. Later, a two-dimensional CFD optimization study with six independent, non-dimensional geometric design variables was carried out, and results showed a 25% higher diodicity for Reynolds number in the range 0 < Re ≤ 2000 compared to commonly used Tesla valve [37]. ...
Article
This article deals with the comparative investigation of instability phenomenon in supercritical CO2 based regular natural circulation loop and a new modified Tesla natural circulation loop. Two-dimensional computational fluid dynamics simulation is carried out for square loops. Fluid flow behaviour and performance of both the loops are determined over a range of pressures (80 bar to 100 bar) and heat inputs (500 W to 2000 W). Results show that the use of a modified Tesla valve leads to better stabilization for all supercritical pressures and heat inputs. It is also found that loop with Tesla mitigates the temperature and velocity oscillations without reducing the heat transfer performance. A good agreement with existing correlations is also obtained in the present study. The unidirectional fluid flow circulation achieved in loop with Tesla valve, makes it an efficient technique to combat instability.
... Even in the field of satellite engineering, this type of valves is reliable, exceeding their minimum life of 23 years in orbit (Wits et al. 2013). Additionally, a lot of effort has been invested in the fabrication methodologies, as well as particular materials that would induce and maintain a certain flow (Qian et al. 2019;Habhab et al. 2016;Truong and Nguyen 2003;Arunachala and Rajat 2019;Gamboa et al. 2005). ...
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In recent years the progress of lab-on-a-chip devices has required the development of moving-parts free microfluidic systems. Different fluid-pumping mechanisms have been explored, such as electroosmotic, magnetohydrodynamic and laser-induced cavitation bubbles. In this work, we report the mathematical modeling of a Tesla valve thermocavitation-based micropump. The model consists of the transient solution of the mass and momentum conservation equations for an incompressible, constant property, Newtonian fluid within different configurations of Tesla valve geometry, implemented in a commercial software. Post-processing of the primary solution focused on the study of the net flow induced by the micropump, and the volumetric efficiency. Performance of the different micropump configurations is discussed in terms of these parameters. Our findings demonstrate that the Tesla valve based geometry for micropumps is versatile depending on its final application, therefore the micropump could be used in a wide variety of applications including drug delivery, fuel delivery for micrometric combustion cells, refrigeration liquids for cooling of microelectronic systems, among others.
... Forster et al. [8] proved the possibility of using Tesla valves in micro--uidics and determined experimentally the diodicity for Reynolds number (Re) 180. Truong et al. in [9] derived numerically the optimum geometry of Tesla valve for < Re < with better diodicity than [8]. Bardell et al [10] analyzed the mechanism of the diodicity and proposed a Tesla valve optimal design for low Re. ...
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In this paper, we deal with topology optimization attributed to the non stationary Navier-Stokes equations. We propose an approach where we analyze the sensitivity of a shape function relating to a perturbation of the flow domain. A numerical optimization algorithm based on topological gradient method is built and applied to the 2D Tesla micro valve reconstruction. Some numerical results confirm the efficiency of the proposed approach.
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Purpose This study aimed to investigate anatomic relationships and biomechanics of pressure-dependent trabecular meshwork and distal valve-like structure deformation in normal and glaucoma eyes using high-resolution optical coherence tomography (HR-OCT). Methods We controlled Schlemm’s canal (SC) pressure during imaging with HR-OCT in segments of three normal (NL) and five glaucomatous (GL) ex vivo eyes. The dissected limbal wedges were studied from 15 locations (5 NL and 10 GL). A minimally invasive glaucoma surgery (MIGS)-like cannula was inserted into the SC lumen, whereas the other end was attached to a switch between two reservoirs, one at 0, the other at 30 mm Hg. A steady-state pressure of 30 mm Hg was maintained to dilate SC and collector channels (CC) during 3D volume imaging. The resulting 3D lumen surface relationships were correlated with internal structural features using an image mask that excluded tissues surrounding SC and CC. While imaging with HR-OCT, real-time motion responses in SC and CC areas were captured by switching pressure from 0 to 30 or 30 to 0 mm Hg. NL vs. GL motion differences were compared. Results Lumen surface and internal relationships were successfully imaged. We identified SC inlet and outlet valve-like structures. In NL and GL, the mean SC areas measured at the steady-state of 0 and 30 mm Hg were each significantly different ( p < 0.0001). Synchronous changes in SC and CC lumen areas occurred in <200 ms. Measured SC area differences at the steady-state 0 and 30 mmHg, respectively, were larger in NL than GL eyes ( p < 0.0001). The SC motion curves rose significantly more slowly in GL than NL ( p < 0.001). Pressure waves traveled from the cannula end along the SC lumen to CC and deep intrascleral channels. Conclusion HR-OCT provided simultaneous measurements of outflow pathway lumen surfaces, internal structures, and biomechanics of real-time pressure-dependent dimension changes. We identified SC inlet and outlet valve-like structures. GL tissues underwent less motion and responded more slowly than NL, consistent with increased tissue stiffness. A MIGS-like shunt to SC permitted pulse waves to travel distally along SC lumen and into CC.
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Reasoning by analogy is powerful in physics for students and researchers alike, a case in point being electronics and hydraulics as analogous studies of electric currents and fluid flows. Around 100 years ago, Nikola Tesla proposed a flow control device intended to operate similarly to an electronic diode, allowing fluid to pass easily in one direction but providing high resistance in reverse. Here, we use experimental tests of Tesla's diode to illustrate principles of the electronic-hydraulic analogy. We design and construct a differential pressure chamber (akin to a battery) that is used to measure flow rate (current) and thus resistance of a given pipe or channel (circuit element). Our results prove the validity of Tesla's device, whose anisotropic resistance derives from its asymmetric internal geometry interacting with high-inertia flows, as quantified by the Reynolds number (here, Re ∼ 10 3). Through the design and testing of new fluidic diodes, we explore the limitations of the analogy and the challenges of shape optimization in fluid mechanics. We also provide materials that may be incorporated into lesson plans for fluid dynamics courses, laboratory modules, and further research projects.
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