Paper:

# CFD Analysis of Friction-Reduction Effect of Micro-Textured Surfaces in Lubricant

## Yue Sun^{*,†}, Shaolin Xu^{**}, Tomoki Kyoizumi^{*}, Keita Shimada^{*}, Masayoshi Mizutani^{*}, and Tsunemoto Kuriyagawa^{*}

^{*}Tohoku University

6-6-1 Aramaki-Aza-Aoba, Aoba-ku, Sendai 980-8579, Japan

^{†}Corresponding author

^{**}South University of Science and Technology, Shenzhen, China

This paper investigates the effects of geometrical features of tailored textures on friction reduction of a surface with a lubricant-film thickness of several to several-tenths micrometers, using the Navier-Stokes equations and the orthogonal experimental design. The results indicate that the surface textured with the selected sawtooth riblets in lubricant can have up to 93.83% less friction than an untextured surface. The thickness of the lubricant film plays the most important role in friction reduction; the height and the ridge angle of the riblets are the secondary factors. The results and principles obtained can potentially be used in the designing of low-friction surfaces in precision machines with transmission parts.

- [1] X. Wang, K. Kato, K. Adachi, and K. Aizawa, “Loads Carrying Capacity Map for the Surface Texture Design of SiC Thrust Bearing Sliding in Water,” Tribology Int., Vol.36, No.3, pp. 189-197, 2003.
- [2] X. Wang, K. Kato, K. Adachi, and K. Aizawa, “The Effect of Laser Texturing of SiC Surface on the Critical Load for the Transition of Water Lubrication Mode from Hydrodynamic to Mixed,” Tribology Int., Vol.34, No.10, pp. 703-711, 2001.
- [3] M. E. Eleshaky, “CFD Investigation of Pressure Depressions in Aerostatic Circular Thrust Bearings,” Tribology Int., Vol.42, No.7, pp. 1108-1117, 2009.
- [4] N. Moronuki, “Functional Texture Design and Texturing Processes,” Int. J. of Automation Technology, Vol.10, No.1, pp. 4-15, 2016.
- [5] I. Etsion, “Improving Tribological Performance of Mechanical Components by Laser Surface Texturing,” Tribology Letters, Vol.17, No.4, pp. 733-737, 2004.
- [6] P. Brajdic-Mitidieri, A. D. Gosman, E. Ioannides, and H. A. Spikes, “CFD Analysis of a Low Friction Pocketed Pad Bearing,” J. of Tribology, Vol.127, No.4, pp. 803-812, 2005.
- [7] Y. Huang and R. F. Salant, “Simulation of a Hydraulic Rod Seal with a Textured Rod and Starvation,” Tribology Int., Vol.95, pp. 306-315, 2016.
- [8] N. Kawasegi, H. Sugimori, N. Morita, and T. Sekiguchi, “Improvement of Machining Performance of Small-Diameter End Mill by Means of Micro- and Nanometer-Scale Textures,” Int. J. of Automation Technology, Vol.10, No.4, pp. 882-890, 2016.
- [9] A. Greidanus, R. Delfos, S. Tokgoz, and J. Westerweel, “Turbulent Taylor-Couette Flow Over Riblets: Drag Reduction and the Effect of Bulk Fluid Rotation,” Experiments in Fluids, Vol.56, No.5, p. 107, 2015.
- [10] A. Ramesh, W. Akram, S. P. Mishra, A. H. Cannon, A. A. Polycarpou, and W. P. King, “Friction Characteristics of Microtextured Surfaces Under Mixed and Hydrodynamic Lubrication,” Tribology Int., Vol.57, pp. 170-176, 2013.
- [11] J. Li and H. Chen, “Evaluation on Applicability of Reynolds Equation for Squared Transverse Roughness Compared to CFD,” J. of Tribology, Vol.129, No.4, pp. 963-967, 2007.
- [12] M. Dobrica and M. Fillon, “About the Validity of Reynolds Equation and Inertia Effects in Textured Sliders of Infinite Width,” Proc. of the Institution of Mechanical Engineers, Part J: J. of Engineering Tribology, Vol.223, No.1, pp. 69-78, 2009.
- [13] S. Cupillard, S. Glavatskih, and M. J. Cervantes, “Computational Fluid Dynamics Analysis of a Journal Bearing with Surface Texturing,” Proc. of the Institution of Mechanical Engineers, Part J: J. of Engineering Tribology, Vol.222, No.2, pp. 97-107, 2008.
- [14] F. Sahlin, S. B. Glavatskih, T. Almqvist, and R. Larsson, “Two-Dimensional CFD-Analysis of Micro-Patterned Surfaces in Hydrodynamic Lubrication,” Trans. of the ASME-F-J. of Tribology, Vol.127, No.1, pp. 96-102, 2005.
- [15] G. Caramia, G. Carbone, and P. De Palma, “Hydrodynamic Lubrication of Micro-Textured Surfaces: Two Dimensional CFD-Analysis,” Tribology Int., Vol.88, pp. 162-169, 2015.
- [16] B. Dean and B. Bhushan, “Shark-Skin Surfaces for Fluid-Drag Reduction in Turbulent Flow: A Review,” Philosophical Trans. of the Royal Society of London A: Mathematical, Physical and Engineering Sciences, Vol.368, No.1929, pp. 4775-4806, 2010.
- [17] R. García-Mayoral and J. Jiménez, “Drag Reduction by Riblets,” Philosophical Trans. of the Royal Society of London A: Mathematical, Physical and Engineering Sciences, Vol.369, No.1940, pp. 1412-1427, 2011.
- [18] M. Scaraggi, F. P. Mezzapesa, G. Carbone, A. Ancona, D. Sorgente, and P. M. Lugarà, “Minimize Friction of Lubricated Laser-Microtextured-Surfaces by Tuning Microholes Depth,” Tribology Int., Vol.75, pp. 123-127, 2014.
- [19] M. Scaraggi, F. P. Mezzapesa, G. Carbone, A. Ancona, and L. Tricarico, “Friction Properties of Lubricated Laser-Microtextured-Surfaces: an Experimental Study from Boundary-to Hydrodynamic-Lubrication,” Tribology Letters, Vol.49, No.1, pp. 117-125, 2013.
- [20] S. V. Patankar and D. B. Spalding, “A Calculation Procedure for Heat, Mass and Momentum Transfer in Three-Dimensional Parabolic Flows,” Int. J. of heat and mass transfer, Vol.15, No.10, pp. 1787-1806, 1972.
- [21] H. Schlichting, “Boundary-Layer Theory, 7th edition,” McCraw-Hill, 1979.
- [22] V. Zouzoulas and C. I. Papadopoulos, “3-D Thermohydrodynamic Analysis of Textured, Grooved, Pocketed and Hydrophobic Pivoted-Pad Thrust Bearings,” Tribology Int., Vol.110, pp. 426-440, 2017.
- [23] G. Taguchi, “System of Experimental Design: Engineering Methods to Optimize Quality and Minimize Costs,” UNIPUB/Kraus Int. Publications, 1987.