Temporal patterns of the maximum scour depth around a pier

In temporal and spatial development of scour processes around a cylindrical pier, the maximum scour depth does not occur at the same location over the time. It localizes at the pier sides firstly, then it tends to migrate towards the pier leading face at a rate mainly depending on the approach flow densimetric Froude number. Based on experiments carried out at University of Basilicata and experiments previously conducted at VAW-ETH, Zurich, this paper would like to provide mainly a relationship for the switch time Tsw, defined as the (dimensionless) time at which the maximum scour depth transfers from the pier sides to the axial pier front. The VAW data were globally processed to identify preventative outcomes. The data collected in the present study were devoted to the capture of Tsw and thus were used for a more detailed analysis. Findings, that appear wide-ranging, would provide useful tools for numerical modeling, field diagnostic and for proper analyses of literature data that are frequently based on observations at pier front only.