Concept vs actuality
Posted by: carldelo on Sep-20-12 10:54 PM (EST)
The stagnation line is not a concept, it is a fact of 3-D fluid flow over an object. It marks the boundary between the flow that goes over one side of the object, vs flow that goes over the other side.
A stagnation line exists on a paddle as it must, because some fluid flows around one side, and some flows around the other. A stagnation point only exists in 2-D flow; flow over a paddle is decidedly 3-D. There is no such thing as a stagnation area. Any intro fluids text should suffice to explain the concept in more detail.
Re: the flutter argument, it's clear to me that the ridge will reduce flutter, based on my experience in experimental fluid mechanics. No one is saying that a ridge is the only, or even the best way of avoiding flutter - that's your supposition, I think.
The fact that you've only seen a ridge on a cheap Euro paddle, and that racers don't use paddles with a ridge means nothing, of course. It's an argument, of course, but not proof of anything, as I think you must admit.