Notice of RetractionThe effect of inner surface roughness on friction factor in horizontal microtubes

Notice of Retraction

After careful and considered review of the content of this paper by a duly constituted expert committee, this paper has been found to be in violation of IEEE´s Publication Principles.

We hereby retract the content of this paper. Reasonable effort should be made to remove all past references to this paper.

The presenting author of this paper has the option to appeal this decision by contacting TPII@ieee.org.

Based on the recent research by Ghajar et al., special attention should be given to the pressure sensing diaphragms for the measurements of friction factor in micro-tubes. In their research, they focused on how the micro-tube diameters influenced the transition region. This study complements their study. Using their suggested diaphragm selection method, micro-tubes with diameters around 1000 μm and five different surface roughness values ranging from 0 to 4.3 μm were used to study the friction factor characteristics across the laminar, transition and turbulent regions (800<;Re<;7000). Moreover, the influence of surface roughness on the start and end of the transition region was observed. It was concluded that a narrower transition region can be seen with an increase in the surface roughness.