Turbulent Stresses at the Bottom Surface near an Abutment: Laboratory-Scale Numerical Experiment

The flow field around a bridge abutment is analyzed by means of large eddy simulation. The geometrical configuration corresponds to the initial condition of a scour process (flat bed). The three-dimensional flow structure in front of the abutment is analyzed with special emphasis on its effects on shear stresses and pressure gradients on the bottom wall which, in turn, are discussed with respect to their potential scouring action. Both first- and second-order statistics around the abutment are quantitatively discussed, together with probability density distributions of stresses in specific locations. The investigation shows that several terms may play a relevant role in sediment transport around the obstacle. Specifically, the mean horizontal pressure gradient may reach values as large as two orders of magnitude that of a canonical boundary layer, whereas the instantaneous vertical pressure gradient may give an uplifting force comparable to the immersed weight of the sediment. The analysis suggests that l...

[1]  Albert Molinas,et al.  Shear Stress around Vertical Wall Abutments , 1998 .

[2]  Anthony J. Grass,et al.  Initial Instability of Fine Bed Sand , 1970 .

[3]  António H. Cardoso,et al.  Effects of Time and Channel Geometry on Scour at Bridge Abutments , 1999 .

[4]  Bruce W. Melville,et al.  Local scour and flow measurements at bridge abutments , 1994 .

[5]  Jochen Fröhlich,et al.  Highly resolved large-eddy simulation of separated flow in a channel with streamwise periodic constrictions , 2005, Journal of Fluid Mechanics.

[6]  Gary Parker,et al.  Bedload transport in the case of seepage flow , 2006 .

[7]  Denis Dartus,et al.  THREE-DIMENSIONAL COMPUTATION OF FLOW AROUND GROYNE , 1997 .

[8]  W. Hager,et al.  Temporal Evolution of Clear-Water Pier and Abutment Scour , 2002 .

[9]  Vincenzo Armenio,et al.  LARGE EDDY SIMULATION OF SECONDARY FLOWS OVER LONGITUDINALLY-RIDGED WALLS , 2001, Proceeding of Second Symposium on Turbulence and Shear Flow Phenomena.

[10]  Fotis Sotiropoulos,et al.  Coherent Structures in Flat-Bed Abutment Flow: Computational Fluid Dynamics Simulations and Experiments , 2003 .

[11]  Thorsten Stoesser,et al.  Turbulence Structures in Flow over Two-Dimensional Dunes , 2008 .

[12]  Abdul,et al.  VORTEX FLOW FIELD IN A SCOUR HOLE AROUND ABUTMENTS , 2003 .

[13]  Hans J. Leutheusser,et al.  Turbulent Flow in Rectangular Ducts , 1963 .

[14]  Nallamuthu Rajaratnam,et al.  Flow Near Groin‐Like Structures , 1983 .

[15]  J. Koseff,et al.  A non-staggered grid, fractional step method for time-dependent incompressible Navier-Stokes equations in curvilinear coordinates , 1994 .

[16]  P. Spalart.  Comments on the feasibility of LES for wings, and on a hybrid RANS/LES approach , 1997 .

[17]  Walter Tollmien,et al.  Über die ausgebildete Turbulenz , 1961 .

[18]  U. Piomelli,et al.  Turbulent structures in accelerating boundary layers , 2000 .

[19]  Abdul Karim Barbhuiya,et al.  Velocity and turbulence in a scour hole at a vertical-wall abutment , 2006 .

[20]  C. Meneveau,et al.  A Lagrangian dynamic subgrid-scale model of turbulence , 1994, Journal of Fluid Mechanics.

[21]  B. Sumer.  Mathematical modelling of scour: A review , 2007 .

[22]  Francesco Ballio,et al.  Scour development and sediment motion at rectangular and trapezoidal abutments , 2006 .

[23]  Jørgen Fredsøe,et al.  Influence of turbulence on bed load sediment transport , 2003 .

[24]  Abdul Karim Barbhuiya,et al.  3D flow field in a scour hole at a wing-wall abutment , 2006 .

[25]  Willi H. Hager,et al.  Shields' Entrainment Criterion in Bridge Hydraulics , 2002 .

[26]  B. Sumer,et al.  Numerical and experimental investigation of flow and scour around a circular pile , 2005, Journal of Fluid Mechanics.

[27]  T. Hosoda,et al.  Three-Dimensional Numerical Model for Flow and Bed Deformation around River Hydraulic Structures , 2005 .

[28]  A. K. Barbhuiya,et al.  Flow field at a vertical-wall abutment , 2005 .

[29]  J. P. Martín-Vide.  Local scour in a protruding wall on a river bank , 2007 .

[30]  R. L. Shreve,et al.  Role of Near‐Bed Turbulence Structure in Bed Load Transport and Bed Form Mechanics , 1995 .

[31]  Vincenzo Armenio,et al.  A Lagrangian Mixed Subgrid-Scale Model in Generalized Coordinates , 2000 .

[32]  K. Babaeyan-Koopaei,et al.  Appraisal of a Geometric Model for Self-Formed Channels in Uniform Sand , 1997 .

[33]  Y. Dubief,et al.  On coherent-vortex identification in turbulence , 2000 .

[34]  Subhasish Dey,et al.  Sediment Pickup on Streamwise Sloping Beds , 2001 .

[35]  Stefano Malavasi,et al.  Sediment Kinematics in Abutment Scour , 2008 .

[36]  John Kim,et al.  DIRECT NUMERICAL SIMULATION OF TURBULENT CHANNEL FLOWS UP TO RE=590 , 1999 .

[37]  Francesco Ballio,et al.  A Survey of Time-Averaged Characteristics of Laminar and Turbulent Horseshoe Vortices , 1998 .

[38]  Asmund Huser,et al.  Direct numerical simulation of turbulent flow in a square duct , 1992 .

[39]  Abdul Karim Barbhuiya,et al.  Time Variation of Scour at Abutments , 2005 .

[40]  Nallamuthu Rajaratnam,et al.  Observations on Flow around Bridge Abutment , 2000 .