Fully developed forced convection through semicircular ducts

There is a lot of literature on convection through ducts of different cross-sectional geometry. The problems range from steady-state fully developed convection to transient convection at the tube entrance. Furthermore, twisted-tape inserts inside circular tubes are a particularly effective technique for enhancing laminar flow heat transfer in circular tubes. The swirl flow effects diminish as the severity of the twist is decreased. In the limit, the strip is straight and the tube is divided into two circular segment ducts. Two different thermal boundary conditions were considered. The first was the axially constant heat flux and uniform wall temperature around the entire semicircular tube at each axial location; whereas the second was axially constant heat flux and uniform wall temperature around the semicircular portion and an insulated wall at the flat portion.