So I'm designing an impeller and rather than how to prevent cavitation, I'd like to know how to cause cavitation. I've read up on fluid shear stress and Couette flow, but this all appears to be based on relative velocity dV, of parallel discs, separated by a small distance dX, and fluid of viscosty μ. Shear Stress, τ = μ dV/dx. I also read that cavitation occus when pressure exceeds vapour pressure for the given fluid a the given temperature (3.2 kN/m2 for water @ 25 oC). I'm happy to accept all this. What I don't think I understand is how the geometry of the impeller affects cavitation. Videos of a cavitating marine propeller show the cavitation bubbles all the way along the length of the leading edge, right from the hub to the tip, but not on the hub (despite the hub having the same relative velocity as the leading edge, close to the hub). This suggests to me that geometry does play a role in caviaton, not just relative velocity. I'd exect an impeller with a very square leading edge to cavitate at a lower relative veloity than a very sharp leading edge. Is this a reasonable thought? In water at 25 oC at 1500rpm, my 80mm impeller seems to produce a shear stress of 22.4 Pa Nowhere near the 3'200 Pa required for cavitation. Further calculations seem to indicate that to get an 80mm impeller to cavitate would require it to rotate at 215'000 rpm! Surely cavitation is dependant on more than just diameter? I have Solidworks Simulation and plan on verifying results with this, but I'd like to have some idea if what Solidworks tells me is correct. Thanks for ANY help anyone can provide!