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您的检索式：作者名="Alexander L.Forrest"
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| 1 | Predicting scour beneath subsea pipelines from existing small free span depths under steady currents显示文摘An equation was developed to predict current-induced scour beneath subsea pipelines in areas with small span depths,S.Current equations for scour prediction are only applicable to partially buried pipelines.The existence of small span depths(i.e.S/D<0.3)are of concern because the capacity for scour is higher at smaller span depths.Furthermore,it is impractical to perform rectification works,such as installing grout bags,under a pipeline with a small S/D.Full-scale two-dimensional computational fluid dynamics(CFD)simulations were performed using the Reynolds-averaged Navier-Stokes approach and the Shear stress transport k-ωturbulence model.To predict the occurrence of scour,the computed maximum bed shear stress beneath the pipe was converted to the dimensionless Shields parameter,and compared with the critical Shields parameter based on the mean sediment grain size.The numerical setup was verified,and a good agreement was found between model-scale CFD data and experimental data.Field data were obtained to determine the mean grain size,far field current velocity and to measure the span depths along the surveyed pipe length.A trend line equation was fitted to the full-scale CFD data,whereby the maximum Shields parameter beneath the pipe can be calculated based on the undisturbed Shields parameter and S/D. | Jun Y.Lee Jasmin McInerney Remo Cossu Zhi Q.Leong Alexander L.Forrest | 2017 | Journal of Ocean Engineering and Science2017，2，2： | 2 |
| 2 | Development of current-induced scour beneath elevated subsea pipelines显示文摘When scour occurs beneath a subsea pipeline and develops to a certain extent,the pipeline may experience vortex-induced vibrations,through which there can be a potential accumulation of fatigue damage.However,when a pipeline is laid on an uneven seabed,certain sections may have an elevation with respect to the far-field seabed,e o,at which the development of scour would vary.This work focused on predicting the development of the scour depth beneath subsea pipelines with an elevation under steady flow conditions.A range of pipe elevation-to-diameter ratios(i.e.0≤e o/D≤0.5)have been considered for laboratory experiments conducted in a sediment flume.The corresponding equilibrium scour depths and scour time scales were obtained;experimental data from published literature have been collected and added to the present study to produce a more complete analysis database.The correlation between existing empirical equations for predicting the time scale and the experimental data was assessed,resulting in a new set of constants.A new manner of converting the scour time scale into a non-dimensional form was found to aid the empirical equations in attaining a better correlation to the experimental data.Subsequently,a new empirical equation has also been proposed in this work,which accounts for the influence of e o/D on the non-dimensional scour time scale.It was found to have the best overall correlation with the experimental data.Finally,full-scale predictions of the seabed gaps and time scales were made for the Tasmanian Gas Pipeline(TGP). | Jun Y.Lee Alexander L.Forrest Fauzi A.Hardjanto Shuhong Chai Remo Cossu Zhi Q.Leong | 2018 | Journal of Ocean Engineering and Science2018，3，4： | 0 |
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