Tribology and Lubricants

Korean Tribology Society (한국트라이볼로지학회)
권호 표지
DOI QR코드

DOI QR Code

A Study on the Anisotropic Flow Characteristics of Droplets on Rice Leaf Surface

벼 잎 표면에서 액적의 이방성 흐름 특성에 관한 연구

  • Kim, Tae Wan (Department of Mechanical Engineering, Pukyong National University)
  • 김태완 (부경대학교 기계공학과)
  • Received : 2017.10.03
  • Accepted : 2017.11.15
  • Published : 2017.12.31
Download PDF
⟨ Previous Next ⟩

Abstract

In this study, we aimed to clarify the wettability and anisotropic flow characteristics of rice leaves as a basic study for engineering applications of anisotropic flow characteristics of rice leaf surface. To investigate the surface structure of rice leaf, the micro grooves and asperities of rice leaves were analyzed and quantified by scanning electron microscope, Confocal laser scanning microscopy, and stylus profilometer. The analysis of the structure of rice leaf surface confirmed that asymmetrical cone - like protrusions in leaf veins were inclined toward the leaf tip. The static contact angle test showed that the contact angle at the midline vein or leaf vein location where the micropapilla is concentrated is about $20^{\circ}$ higher than the leaf blade position. The contact angles of fresh and dried rice leave were also compared. The dried rice leaves showed a contact angle of about $5^{\circ}$ to $15^{\circ}$ higher than that of fresh leaves, suggesting that the volume of the protrusions decreased as the water was removed, thus reducing the contact area with the droplet. In the contact angle history test the hysteresis in the leaf tip direction was found to be much lower than that in the leaf petiole direction. This results can be explained that asymmetrical cone - like protrusions had a significant effect on the droplet flow characteristics through contact angle hysteresis experiment.

Keywords

References

  1. Barthlott, W., Neinhuis, C., "Purity of the sacred lotus, or escape from contamination in biological surfaces", Planta., Vol. 202, pp. 1-8, 1997. https://doi.org/10.1007/s004250050096
  2. Bixler, G. D., Bhushan, B., "Fluid drag reduction and efficient self-cleaning with rice leaf and butterfly wing bioinspired surfaces", Nanoscale, Vol. 5, pp. 7685-7710, 2013. https://doi.org/10.1039/c3nr01710a
  3. Zheng, Y., Gao, X., Jiang, L., "Directional adhesion of superhydrophobic butterfly wings", Soft Matter., Vol. 3, pp. 178-182, 2007. https://doi.org/10.1039/B612667G
  4. Feng, L., Li, S., Li, L., Li, H., Zhang, L., Zhai, J., Song, Y., Liu, B., Jiang, L., Zhu, D., "Super-hydrophobic surfaces from natural to artificial", Adv. Mater., Vol. 14, pp. 1857-1860, 2002. https://doi.org/10.1002/adma.200290020
  5. Wang, X., Hu, H., Ye, Q., Gao, T., Zhou, F., Xue, Q., "Superamphiphobic coatings withcoralline-like structure enabled by one step spray of polyurethane/carbonnanotube composites", J. Mater. Chem., Vol. 22, pp. 9624-9631, 2012. https://doi.org/10.1039/c2jm30744h
  6. Lee, S. M., Jung, I. D., Ko, J. S., "The effect of the surface wettability of nanoprotrusions formed on network-type microstructures", J. Micromech. Mocroeng., Vol. 18, pp. 125007, 2008. https://doi.org/10.1088/0960-1317/18/12/125007
  7. Park, C. I., Jeong, H. E., Lee, S. H., Cho, H. S., Suh, K. Y., "Wetting transition and optimal design for microstructured surfaces with hydrophobic and hydrophilic materials", J. Colloid. Interf. Sci., Vol. 336, pp. 298-303, 2009 https://doi.org/10.1016/j.jcis.2009.04.022
  8. Rahmawan, Y. Moon, M.-W. Kim, K.-S., Lee, K.-R., Suh, K. Y., "Wrinkled, Dual-Scale Structures of Diamond-Like Carbon (DLC) for Superhydrophobicity", Langmuir, Vol. 26, pp. 484-491 2010. https://doi.org/10.1021/la902129k
  9. Genzer, J., Marmur, A., "Biological and synthetic self cleaning surfaces", MRS Bulletin, Vol. 33, pp. 742-746, 2008. https://doi.org/10.1557/mrs2008.159
  10. Sirovich, L., Karlsson, S., "Turbulent drag reduction by passive mechanisms", Nature, Vol. 388, pp. 753-755, 1997. https://doi.org/10.1038/41966
  11. Lee, S. J., Jang, Y. G., "Control offlow around a NACA 0012 airfoil with a micro-riblet film", J. Fluids, Vol. 20, pp. 659-672, 2005.
  12. Kong, Y. S., Kim, T. W., "Wettability of Biomimetic Riblet Surface like Shark Skin", J. KSTLE, Vol. 29, pp. 304-309, 2013.
  13. Kim, T. W., "Assessment of hydro/oleophobicity for shark skin replica with riblets", J. Nanosci. and Nanotechno., Vol. 14, pp. 1-7, 2014. https://doi.org/10.1166/jnn.2014.9265
  14. J. Yang, F. R. A. J. Rose, N. Gadegaared, M. R. Alexander, "Effect of sessile drop volume on the wetting anisotropy observed on grooved surfaces", Langmuir., Vol. 25, pp. 2567-2571, 2009. https://doi.org/10.1021/la803942h
  15. A. D. Sommers, A. M. Jacobi, "Wetting phenomena on micro-grooved aluminum surfaces and modeling of the critical droplet size", J. Colloid Interface Sci., Vol. 328, pp. 402-411, 2008. https://doi.org/10.1016/j.jcis.2008.09.023
  16. Guo, P., Lu, Y., Ehmann, K., Cao, J., 2014, "Generation of Hierarchical Micro-Structures for Anisotropic Wetting by Elliptical Vibration Cutting", CIRP Annals-Manufacturing Technology, Vol. 63, pp. 553-556, 2014. https://doi.org/10.1016/j.cirp.2014.03.048
  17. Ma, C., Bai, S., Peng, X., Meng, Y., "Wettability of laser regular protuberant texturing on silicon carbide surface," Appl. Surf. Sci., pp. 26651-26656, 2013.

Cited by

  1. Laser Groove 표면의 젖음 특성에 관한 연구 vol.35, pp.5, 2017, https://doi.org/10.9725/kts.2019.35.5.294