Abstract
Drag-reducing turbulent flows of dilute polymer solution are measured using particle tracking velocimetry (PTV). The measurements are done in a micro channel 2 mm in wall-to-wall distance for the Reynolds numbers of about 300 and 10, 000. A double-pulsed Nd : YAG laser is used to illuminate 0.8μ-diameter acrylic tracer particles. It is confirmed that the turbulent drag reduction in polymer solution (i.e., Toms effect) becomes more pronounced in small conduits like the present micro channel than in other larger channels and pipes. The mean velocity profile in drag-reducing flows looks like the laminar velocity profile. The turbulence statistics measured in drag-reducing flows have shown that the streamwise and wall-normal velocity fluctuations, when normalized with the friction velocity, are approximately of the same magnitude as those in pure water flows but that the Reynolds stress almost vanishes. Separate PIV measurements indicate that the presence of elongated structures of streamwise velocity fluctuations contributing little to the generation of the Reynolds stress is the reason for the measured turbulence characteristics in the drag-reducing micro channel flows
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
