Hello all, i hope you're having a nice day.

I have a question about analytical heat transfer coefficient (HTC) calculation/determination for a rectangular duct curved in a circle. I have found some literature on this topic and also found empirical equations for rectangular cross section straight water ducts/pipes heat transfer calculation based on dimensions of the duct and also some equations for circular cross section helical pipe coil HTC calculation [1]. But none for my specific problem. I know that with curvature of the pipe/duct, the HTC increases as a result of centrifugal forces inducing radial pressure gradient. Has any of you dealt with something similar in the past? If anyone has any experience or can recommend me some literature for my problem or help me in any other way I would be very grateful.

Best regards!

Gal Štempihar

[1] BERGMAN, Theodore L. *Fundamentals of heat and mass transfer*. John Wiley & Sons, 2011.