Numerical investigation of Tesla valves with a variable angle

A Tesla valve is a passive check valve but with no-moving parts. The unique diode nature of Tesla valves makes them attractive for fluid control in many engineering fields, such as microfluidic systems and hydrogen fuel systems. The effectiveness of a single-stage Tesla valve can be modified by changing its geometric parameters. In this study, four groups of Tesla valves by changing the angle between 45° and 90° are examined. Numerical and mathematical methods are used to compare the diode characteristics of the four groups of Tesla valves, and proper orthogonal decomposition is applied to analyze the main flow fields. Of particular interest is that the diode property is induced by separation bubbles, with those near the left junction of the Tesla valve providing the main control mechanism for the fluid flow. For the forward flow, the main bubble pushes the fluid into the straight channel, while for the reverse flow, the main bubble blocks the outlet of the Tesla valve, making it difficult for fluid to flow out. Notably, our findings suggest that the diode performance of Tesla valves is optimal at θ = 70–80°. The results presented in this paper identify the functional relationship between the angle of the Tesla valve, Reynolds number, and diodicity, and suggest strategies for the optimal design and performance predictions of Tesla valves.