The main purpose of this paper is to analyze the influence of different turbulence flow models on scouring pit of bridge-pier. Flow-3D software is applied in line with the purpose. The key motivation for this study is...The main purpose of this paper is to analyze the influence of different turbulence flow models on scouring pit of bridge-pier. Flow-3D software is applied in line with the purpose. The key motivation for this study is to contribute to the Flow-3D software by means of some modification and adjustment in the sediment scour model and shallow water model. An assessment of turbulence model adopted with the parameters of the Melville experiment to estimate the maximum scour-depth was performed. In the simulation results, the alternate eddy formation and shedding were repeated while the Karman vortex street formed behind the pier for the large eddy simulation LES turbulence model is more realistic in the flow phenomenon. The results of the scour development of large eddy simulation (LES) turbulence model were found to be more satisfied than the Renormalized group (RNG) turbulence model and close to the prior experiment results. The simulated scour results were significantly different with the observed data collected from previous literature in the reason of some unsuitability of meshing method in Flow-3D software.展开更多
Two independent versions of the RNG based k ε turbulence model in conjunction with the law of the wall have been applied to the numerical simulation of an axisymmetric turbulent impinging jet flow field. The two m...Two independent versions of the RNG based k ε turbulence model in conjunction with the law of the wall have been applied to the numerical simulation of an axisymmetric turbulent impinging jet flow field. The two model predictions are compared with those of the standard k ε model and with the experimental data measured by LDV (Laser Doppler Velocimetry). It shows that the original version of the RNG k ε model with the choice of C ε1 =1.063 can not yield good results, among them the predicted turbulent kinetic energy profiles in the vicinity of the stagnation region are even worse than those predicted by the standard k ε model. However, the new version of RNG k ε model behaves well. This is mainly due to the corrections to the constants C ε1 and C ε2 along with a modification of the production term to account for non equilibrium strain rates in the flow.展开更多
文摘The main purpose of this paper is to analyze the influence of different turbulence flow models on scouring pit of bridge-pier. Flow-3D software is applied in line with the purpose. The key motivation for this study is to contribute to the Flow-3D software by means of some modification and adjustment in the sediment scour model and shallow water model. An assessment of turbulence model adopted with the parameters of the Melville experiment to estimate the maximum scour-depth was performed. In the simulation results, the alternate eddy formation and shedding were repeated while the Karman vortex street formed behind the pier for the large eddy simulation LES turbulence model is more realistic in the flow phenomenon. The results of the scour development of large eddy simulation (LES) turbulence model were found to be more satisfied than the Renormalized group (RNG) turbulence model and close to the prior experiment results. The simulated scour results were significantly different with the observed data collected from previous literature in the reason of some unsuitability of meshing method in Flow-3D software.
文摘Two independent versions of the RNG based k ε turbulence model in conjunction with the law of the wall have been applied to the numerical simulation of an axisymmetric turbulent impinging jet flow field. The two model predictions are compared with those of the standard k ε model and with the experimental data measured by LDV (Laser Doppler Velocimetry). It shows that the original version of the RNG k ε model with the choice of C ε1 =1.063 can not yield good results, among them the predicted turbulent kinetic energy profiles in the vicinity of the stagnation region are even worse than those predicted by the standard k ε model. However, the new version of RNG k ε model behaves well. This is mainly due to the corrections to the constants C ε1 and C ε2 along with a modification of the production term to account for non equilibrium strain rates in the flow.
