The Use of a Transformed Boundary Condition in Modelling Air Compression During Infiltration

A computer‐based numerical analysis incorporating a time‐dependent surface boundary condition transformation is of value in modelling the air compression effects which occur during ponded infiltration in bounded columns. However, the transformation requires clarification when used with materials which exhibit a well‐defined water entry value. Since the capillary pressure head has no meaning in the saturated zone, which develops from the surface downwards during the infiltration process, it is necessary to define a pseudocapillary pressure head for this zone. This concept assists in developing a consistent qualitative argument showing that the one‐phase, one‐dimensional analysis accurately models the bounded flow regime. The condition which governs the termination of the analysis upon air escape is also considered.