A transient analysis is often necessary (for example, in problems where a moving structure closes the gap). When there is contact, it is prudent to use a nonlinear analysis to model the contact more accurately. A linear transient analysis can be performed when the gap between a moving structure and a fixed surface remains relatively large. For information on the linear and nonlinear Reynolds equations, refer to Flow Between Flat Surfaces in the Mechanical APDL Theory Reference.

For transient analysis example problems, see Simplified Transient Analysis and Complex Transient Analysis.