Bridges and Environment: Development of an Iterative Scouring Procedure for Implementation in CFD Code for Different Bridge Flooding Conditions

The objective of this study was to develop a simulation model to predict the final shape and size of scour-pit under the flooded bridge deck. A computational methodology has been developed in C++ code and implemented in STAR-CD, a commercial CFD application software, using a BASH script in UNIX environment. For the evolution of the scour-pit shape and depth, a single-phase (re)moving boundary formulation has been developed, based on the computational fluid dynamics analysis of the flow fields around the flooded bridge deck and the shear stress at the bottom-wall, using the High Reynolds number k - epsilon turbulence model with standard wall function. The "scouring tool" was assumed to be the excess shear stress over the critical shear stress, the latter corresponding to the scoured bottom-wall material structure. Comparison with limited experimental data obtained from Turner-Fairbanks Highway Research Center, McLean, VA, USA, revealed larger discrepancies than expected; however, the developed iterative scouring methodology works well with the commercial CFD software and has potential for further enhancement, by including other flow parameters influencing complex scouring process, in addition to the shearing stresses.