Assessing the flow field around an oblong bridge pier. Vectrino acquisition time sensitivity analysis

Abstract

Local scour has been widely identified as one of the primary threats to bridge pier stability. To better understand how the turbulent flow field modified by bridge piers interacts with the bed surface, it is relevant to assess the flow structures that are potentially sufficient to remove the bed material. Thus, the accuracy and measurement quality in estimating the flow field is of primordial importance, mainly in a well-controlled laboratory environment. In the present study, time-averaged velocities and Reynolds shear stresses were measured by using a high-resolution acoustic velocimeter. Due to the highly turbulent nature of the flow, an assessment of the signal acquisition time’s influence on the statistics of turbulent quantities is performed, including the inherent uncertainties regarding the flow field measurement technique. The re-sults showed that the required sampling time for mean and fluctuation velocities, and the lateral Reynolds shear stress, differ by one order of magnitude.