Comparison of Turbulence Models for Simulation of flow Around the Submerged Bridge Decks

During a critical river flood event, a bridge deck may become partially or completely submerged by
the flow. The deck submergence may be a critical condition for structural stability of river bridges. In
this paper, the mean flow fields around a submerged bridge deck and the time averaged drag
coefficient on it have been simulated by using FLUENT software. The turbulence models considered
are the standard k 
, renormalization group (RNG) k 
and Realizable k 
. In these simulations,
the VOF and rigid lid methods have been used for free surface simulation. Reconstruction and Finite
volume schemes have been used to determine the position of the free surface in VOF method and the
results have been compared. Simulation results of time averaged drag coefficient show that in the case
of partially submerged deck, Geometric Reconstruction Scheme in VOF method with standard
turbulence model is in better agreement with the experimental results. In the case of fully submerged
deck, RNG k 
and Realizable k 
turbulence models provide better accuracy than standard
turbulence model. Also, simulation results show that Reconstruction based schemes in VOF
method are not capable to simulate mixing of water and air and finite volume schemes have to be used
for mixing of water and air simulation.