Transitional and Turbulent Flow Modeling in a Tesla Valve

Abstract

A Tesla valve is a fluidic dioide that may be used in a variety of mini/micro channel applications for passive flow rectification and/or control. The valve’s effectiveness is quantified by the diodicity, which is primarily governed by the incoming flow speed, its design and direction-dependent minor losses throughout its structure during forward and reverse flows. It has been previously shown that the Reynolds number at the valve inlet is not representative of the entire flow regime throughout the Tesla structure. Therefore, pure-laminar solving methods are not necessarily accurate. Local flow instabilities exist and exhibit both transitional and turbulent characteristics. Therefore, the current investigation seeks to identify a suitable RANS-based flow modeling approach to predict Tesla valve diodicity via three-dimensional (3D) computational fluid dynamics (CFD) for inlet Reynolds numbers up to Re = 2,000. Using ANSYS FLUENT (v. 14), a variety of models were employed, including: the Realizable k-ε, k-kL-ω and SST k-ω models. All numerical simulations were validated against available experimental data obtained from an identically-shaped Tesla valve structure. It was found that the k-ε model drastically under-predicts experimental data for the entire range of Reynolds numbers investigated and cannot accurately model the Tesla valve flow. The k-kL-ω and SST k-ω models approach the experimentally-measured diodicity better than regular 2D CFD. The k-kL-ω demonstrates exceptional agreement with experimental data for Reynolds numbers up to approximately 1,500. However, both the k-kL-ω and k-ω SST models over-predict experimental data for Re = 2,000.

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

“…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.…”

Tesla Valve Microfluidics: The Rise of Forgotten Technology

“…STV design is the most straightforward TV structure and is widely used in microfluidics devices due to its simplicity and ease of fabrication [15,[24][25][26][27][28][29][30][31][32][33]. It consists of a nonperiodic single tesla pattern connected in a microfluidic channel.…”

High-diodicity impinging injector design for rocket propulsion enabled by additive manufacturing

“…The flow path geometry of a Tesla valve promotes flow losses in the reverse direction from abrupt momentum changes, vorticity generation, and an adverse pressure gradient [6]. The fluidic diode developed in this work will combine the hydraulic benefits of "tapering" the injector element, demonstrated to be efficient in Ref.…”