# Influence of Baffle Location on the Diodicity of Tesla Valves
## 3 Results and Discussion  
### Influence of Flow Field Non-Uniformity at One Location on the Diodicity  
Firstly, we compare the impact of four distinct baffle placement methods on the diodicity of TVs, as illustrated in Figure 2. Figure 9 indicates that, in Case 1, the introduction of baffles diminishes the diodicity. For Case 2, when the inlet Reynolds number is below 200, the diodicity is poorer than that without baffles. Conversely, when the inlet Reynolds number exceeds 200, the inclusion of baffles marginally enhances the diodicity, yet the improvement is not markedly significant. Thus, neither Case 1 nor Case 2 effectively optimizes the diodicity. In contrast, Cases 3 and 4, which feature baffles positioned at the reverse inlet, can substantially improve the performance of the TV. Notably, Case 4 significantly optimizes the diodicity, with the diodicity value increasing by approximately 30% relative to the TV without baffles. To attain a higher Di, the objective is to maximize reverse pressure drop(\(\Delta P_{r}\)) and minimize forward pressure drop (\(\Delta P_{f}\)). The incorporation of baffles in this study inevitably introduces additional resistance to fluid flow, thereby augmenting the overall pressure drop \(\Delta P\). Hence, optimizing the Di in the TV design should focus on increasing \(\Delta P_{r}\) to \(\Delta P_{f}\). Consequently, the analysis of the TV's diodicity should begin with the pressure drops during forward flow (\(\Delta P_{f}\)) and reverse flow (\(\Delta P_{r}\)). As depicted in Figure 10a,b, the four cases with integrated baffles demonstrate varying levels of enhancement in pressure drop relative to the TV without baffles. A significant discrepancy in pressure drop is observed between Case 1 and Cases 2, 3, and 4 during reverse flow. Nevertheless, Case 4 stands out with a pronounced difference in pressure drop when compared to Cases 1, 2, and 3 during forward flow. Consequently, these cases should be categorized and examined in a grouped manner to delve deeper into this phenomenon from a fluid dynamics standpoint. In a TV, the fluid's velocity field is not randomly distributed; rather, it is stabilized by the valve's internal geometric structure and the fluid's physical properties, which include velocity, viscosity, and density. The velocity fields for both forward and reverse flows within the TV are illustrated in Figures 11-14. An analysis of the forward and reverse flow fields discussed previously enables us to deduce that the incorporation of baffles within the TV can alter the pressure drop across it, thereby affecting its diodicity. Baffles positioned in regions of high velocity can lead to a significant increase in pressure drop, whereas those in low-velocity areas result in a more moderate increase. Upon comparing the flow field results from Case 1 to Case 4, it becomes apparent that, during forward inflow, the fluid predominantly traverses the straight channel branch located below the arc channel branch, resulting in essentially uniform drag along the path. However, the presence of baffles reduces the channel's cross-sectional area, leading to a non-uniform flow field in the  
Figure 10: Pressure drops over various Tesla valve cases (from cases 1 to 4). (a) Forward flow and (b) reverse flow. Figure 9: Diodicity trend of Tesla valves with and without baffles. vicinity of the baffles and an increase in local resistance. Consequently, the forward inflow pressure drop increases following the addition of baffles. It is noteworthy that the non-uniform flow fields generated by baffles at various positions display distinct variations. As shown in Figures 11 and 12, in Case 4, the baffle is situated in a region of reduced flow velocity, which can be analogous to a vortex that diminishes the impedance to fluid flow. Consequently, the resultant increase in pressure drop is comparatively minor. Figure 11: Comparison of the reverse flow field of Tesla valves with baffles (case 2, 3, 4) and without baffles.