Effect of entrance condition on frictional losses and transition to turbulence in minichannel flows

Levi Campbell
Satish Kandlikar

Proceedings of the second international conference on microchannels and minichannels, June 17-19, 2004. The complete proceedings can be found at www.asme.org . Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works in February 2014.


In studying the fluid flow and heat transfer in microchannels and minichannels, various claims have been made regarding transition at Reynolds numbers significantly below 2300. As a first step in identifying the reasons for such reports on early transition, the effect of entrance geometry on the pressure drop and transition to turbulence was studied in a conventional channel of 19 mm inside diameter (Kandlikar and Campbell [1]). As a second step, the effect of entrance condition on pressure drop and transition to turbulence is studied in small channels with diameters of 1.067 mm and 0.457 mm. The two entrance conditions employed for both channels are re-entrant and smooth. The experimental results show the effect of entrance condition on local friction factor, transition Reynolds number, and Hagenbach’s factor. Keywords: entrance length, pipe flow, transition, laminar, turbulent, minichannel.