from playing with 3d printed tesla valves , I think that you're right that surface distortions hinder correct flow. The way that I created a 3d printed tesla v

from playing with 3d printed tesla valves , I think that you're right that surface distortions hinder correct flow. The way that I created a 3d printed tesla valve that worked was by messing with overall scale. Bigger works better, until suddenly it doesn't work at all. The idea I had previously about why scale may help was the idea that the scale is gradually turning down the amount that the flow error affects the entire system until eventually the mass of the fluid induces more 'error' into the system until the whole thing destabilizes. In other words : with 3d printed tesla valves it's vital to find the sweet scale spot between surface-level distortion causing chaos when the valve itself is too small and liquid mass causing chaos when the valve is too big. That margin between chaos and stability may be made wider by using a finer manufacturing technique, like milling or even SLA/SLS versus FDM. I bet that'd give a wider range of usable sizes. all that said : even professionally made tesla valves must be made with certain scale constraints in mind. I believe those constraints are first-and-foremost a property of the liquid that's going to be transported.