A numerical analysis is conducted to investigate the elastohydrodynamic effect of deterministic microasperities on the shaft of a lip seal. Various geometries of microasperities (triangular, square, hexagonal, and circular) are put into a 100-by-100-μm unit cell and are investigated using Reynold’s Equation. For each shape, the area fraction of the microasperity is varied between 0.2 and 0.8, and the asperity height is varied between 0.3 and 5 micron. The calculation for load capacity and friction coefficient indicates that there are values for asperity height where load capacity and friction coefficient are optimized. These optimum heights were reached at 1–3 μm. Although the lip seal surface is considered to be smooth, reverse pumping can still be obtained using an oriented triangular design. The Couette flow rate for this asperity showed lubricant is reverted back toward the seal side 2.6 times more than using a conventional lip seal. The presence of all designs in the lip seal shows significant improvement on lubrication characteristics, i.e. increasing load support and reducing friction coefficient.

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