Volume 80, Number 5, December 2007
|Number of page(s)||5|
|Section||Interdisciplinary Physics and Related Areas of Science and Technology|
|Published online||31 October 2007|
Polymer turbulent drag reduction near the theta point
Department of Polymer Science and Engineering, Inha University - Incheon, 402-751, Korea
2 Department of Physics and Center for Complex Systems, National Central University Chungli, Taiwan 320, ROC
3 Institute of Physics, Academia Sinica - Nankang, Taipei, Taiwan 115, ROC
Accepted: 10 October 2007
Turbulent drag reduction efficiencies (%DR) of aqueous poly (ethylene oxide) solutions at various distances away from the theta temperature () are studied. It is found that only the long-time behavior of %DR of the system is sensitive to in that %DR decays faster for systems closer to the theta-point. Usually, this faster decay is attributed to the faster mechanical molecular degradation (MMD) of polymers in bad solvents produced by turbulence. However, temperature quenches experiments close to show that the apparent faster decrease in %DR for polymers closer to is not due to MMD but rather because of the shrinking of the polymer after they have been injected into the turbulent flow. The relative insensitivity of the initial maximum %DR can be understood if is considered as a function of the flow.
PACS: 83.10.Tv – Structural and phase changes / 83.60.Yz – Drag reduction / 83.80.Rs – Polymer solutions
© Europhysics Letters Association, 2007
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