It can be seen in Fig. 11 that the effect of friction increases with increasing Uη but, in general, is not much pronounced. The results obtained without friction stresses are essentially shifted to the left with respect to the full model, which is related to overall lateral bending-like deformation of the ball caused by friction (note that the ball is rather stiff to bending as the displacements are constrained at its mid-plane). Otherwise, the characteristic values, such as the maximum pressure and the minimum film thickness, are not much affected by friction, although the difference is visible at high entrainment speeds.