Question on D shaped tubing for low velocity fluid flow

[sknguy]

I had read somewhere, a while back, about the benefits of D shaped tubing/channel on flow rates for a fluid as it travels through a bend. I can't recall how great the benefit was for a D shaped channelling. But from what I recall, it was more efficient for the fluid (or gas?) to be pumped through a D shaped tube when making a bend, where the flat portion of the D shaped tube formed the inside of the bend.

The reason I'm asking is mainly out of curiousity, and part interested if there is any benefit to pumping lower velocity water systems. I'm thinking of agricultural spayer systems, by the way. Or even lower velocity fluid systems too.

[Ian P.]

For liquid systems it would only be of value if you were getting cavitation on the inside of a bend. Otherwise, there is very little differenc in the velocity from inside to outside.
In gas systems, there is an opportunity if the velocities and bend radius are such that there is a big difference in density between the inside of the bend and the outside.
For conventional and especially agricultural hydraulic systems, the velocities are low enough that it shoiuld not provide any benefit. If the velocities are high enough to consider this, you likely have pessure drop issues to worry about.