Publisher : The Korean Environmental Sciences Society
DOI : 10.5322/JESI.2013.22.4.407
Title & Authors
A Study of a Hydrophobic Surface: Comparing Pure Water and Contaminated Water Ambrosia, Matthew Stanley; Lee, Chang-Han;
The flow of sewage has been studied for hundreds of years. Reducing drag in pipes can allow sewer to be removed easily and quickly. Drag reduction is not only a macroscale issue. Physical and chemical properties of the nano-scale can affect flow at the macroscopic scale. In this paper the predictability of hydrophobicity at the nano-scale is studied. Molecular dynamics simulations were used to calculate the range of contact angles of water droplets in equilibrium on a pillared graphite surface. It was found that at a pillar height of two graphite layers there was the largest range of contact angles. It is observed that at this height the droplet begins to transition from the Wenzel state to the Cassie-Baxter state. Surfaces with larger pillar heights have much larger contact angles corresponding to a more hydrophobic surface. Silicon dioxide was also simulated in the water droplet. The contaminant slight decreased the contact angle of the water droplet.
Cassie, A. B. D., Baxter, S.,1944, Wettability of porous surfaces, Trans. Faraday Soc., 40, 546-551.
Ewald, P. P., 1921, Die Berchnungoptischer und elektrostatischer Gitterpotentiale, Annalen der Physik, 64, 253-287.
Fowkes, F. M., Harkins, W. D., 1940, The State of Monolayers Adsorbed at the Interface Solid-Aqueous Solution, J. Am. Chem. Soc., 62, 3377-3386.
Gander, W., Golub, J. H., Strebel, R., 1994, Leastsquares fitting of circles and ellipses, BIT, 34, 558-578.
Gao, L., McCarthy, T. J., 2006, The "Lotus Effect" Explained: Two Reasons Why Two Length Scales of Topography Are Important, Langmuir, 22, 2966- 2967.
Jeong, W. J., Ha, M. Y., Yoon, H. S., Ambrosia, M., 2012, Dynamic Behavior of Water Droplets on Solid Surfaces with Pillar-Type Nanostructures, Langmuir, 28, 5360-5371.
Liu, B., Zong, Z., Wang, P., Du, H., 2011, Experimental Study on Water Cut Oil Flowing in Nanometer Coated Pipeline, Proceedings of ICPTT, ASCE, Beijing, 523-531.
Ptasinski, P. K., Nieuwstadt, F. T. M., Van Den Brule, B. H. A. A., Hulsen M. A., 2001, Experiments in Turbulent Pipe Flow with Polymer Additives at Maximum Drag Reduction, Flow, Turbulence and Combustion, 66, 159-182.
Phillips, J. C., Braun, R., Wang, W., Gumbart, J., Tajkhorshid, E., Villa, E., Chipot, C., Skeel, R. D., Kale, L., Schulten. K., 2005, Scalable molecular dynamics with NAMD,J. Comput. Chem., 26, 1781- 1802.
Wenzel, R. N., 1936, Resistance of solid surfaces to wetting by water, Ind. Eng. Chem., 28, 988-994.