Fig. 4 Pure rolling experiment: cen

Fig. 4 Pure rolling experiment: central film thickness evolution with time at a given entrainment velocity hUei = 200 mm/s for lamellar lubricant 1 (full symbols) and 2 (empty symbols). Each symbol corresponds to an average value. Two steps are observed: a linear growth in thickness followed by a stabilization at a value hl after the time tc. The red (lubricant 1) and blue (lubricant 2) solid lines are obtained from the fit of the data to Eq. (6) in the text. Inset: typical contact interferograms observed in the growth and the stationary states (scale = 200 lm) for lubricant 1. The white arrows indicate the flow direction, while the dashed lines emphasize the position of the air/lubricant meniscus in the inlet zone (color figure online)