Current Forces on a Large Pier Near an Existing Pier

2004 ◽  
Author(s):  
Subrata K. Chakrabarti ◽  
Mark McBride
Keyword(s):  
High Reynolds Number ◽  
Fluid Velocity ◽  
Suspension Bridge ◽  
Mooring Line ◽  
Cfd Analysis ◽  
Rectangular Section ◽  
Flow Vorticity ◽  
Physical Model Tests ◽  
High Reynolds ◽  
Consistency Of The Test

A new suspension bridge is being built over the Tacoma Narrows, Washington. The bridge will be placed on a structure mounted on 2 large concrete caissons, which will be exposed to strong currents. The piers are of rectangular section with chamfered edges in the upper portion. The caissons are being built at site while floating and moored in high currents. There are no known analytical methods or experimental data available on such structures at high Reynolds number. In order to determine the forces on the caisson due to current, a series of scaled physical model tests of one of the caissons was carried out. The forces on the new caisson were measured in the presence of the existing bridge pier and the bottom contours of the Narrows were accurately modeled. The model scale was chosen as 1:100 and the tests were performed for the caisson at different drafts. This paper describes the test setup, and measurement system for a series of fixed caisson tests and demonstrates the consistency of the test data. The measured inline drag and transverse lift forces on the fixed caisson at different drafts are presented and the effect of the fluid velocity and flow vorticity on the frequency contents in the forces is discussed. The interaction effect of the neighboring existing pier on the current forces of the new caisson is investigated. Since the measured forces were applied in the design analysis of the caissons, the scaling effect of the model test is also discussed. This paper is accompanied by two other papers, which form a group of three papers related to the project describing the current excitation on the caisson and the associated caisson responses. The other two papers in succession are ref. [1] and ref. [2]. The paper in ref. [1] describes the numerical computation of the current forces on the caisson by a 3-D CFD analysis, while the ref. [2] uses the information from these two papers to determine the motion response of the caissons and the mooring line tensions.

Model Tests on Current Forces on a Large Bridge Pier Near an Existing Pier

2005 ◽  
Vol 127 (3) ◽  
pp. 212-219 ◽  
Author(s):  
Subrata K. Chakrabarti ◽  
Mark McBride
Keyword(s):  
Fluid Velocity ◽  
Three Dimensional ◽  
Suspension Bridge ◽  
Model Tests ◽  
Bridge Pier ◽  
Mooring Line ◽  
Flow Vorticity ◽  
Physical Model Tests ◽  
High Reynolds ◽  
Consistency Of The Test

A suspension bridge is being built over the Tacoma Narrows, Washington. The bridge will be placed on a structure mounted on two large concrete caissons, which will be exposed to strong currents. The piers are of rectangular section with chamfered edges in the upper portion. The caissons are being built at site while floating and moored in high currents. There are no known analytical methods or experimental data available on such structures at high Reynolds number. In order to determine the forces on the caisson due to current, a series of scaled physical model tests of one of the caissons was carried out. The forces on the caisson were measured in the presence of the existing bridge pier and the bottom contours of the Narrows were accurately modeled. The model scale was chosen as 1:100 and the tests were performed for the caisson at different drafts. This paper describes the test setup, and measurement system for a series of fixed caisson tests and demonstrates the consistency of the test data. The measured inline drag and transverse lift forces on the fixed caisson at different drafts are presented and the effect of the fluid velocity and flow vorticity on the frequency contents in the forces is discussed. The interaction effect of the neighboring existing pier on the current forces on the caisson is investigated. Since the measured forces were applied in the design analysis of the caissons, the scaling effect of the model test is also discussed. This paper is accompanied by two other papers, which form a group of three papers related to the project describing the current excitation on the caisson and the associated caisson responses. The other two papers in succession are by Chakrabarti et al. (J. Offshore Mech. Arct. Eng., to be published) and Chakrabarti and McBride (J. Offshore Mech. Arct. Eng., to be published). The paper by Chakrabarti et al. describes the numerical computation of the current forces on the caisson by a three-dimensional analysis, while the paper by Chakrabarti and McBride uses the information from these two papers to determine the motion response of the caissons and the mooring line tensions.

scholarly journals The stability of developing pipe flow at high Reynolds number and the existence of nonlinear neutral centre modes

2011 ◽  
Vol 684 ◽  
pp. 284-315 ◽  
Author(s):  
Andrew G. Walton
Keyword(s):  
Reynolds Number ◽  
Pipe Flow ◽  
High Reynolds Number ◽  
Pipe Wall ◽  
Fluid Velocity ◽  
Nonlinear Effects ◽  
Neutral Curve ◽  
High Reynolds ◽  
The Stability ◽  
Axisymmetric Disturbances

AbstractThe high-Reynolds-number stability of unsteady pipe flow to axisymmetric disturbances is studied using asymptotic analysis. It is shown that as the disturbance amplitude is increased, nonlinear effects first become significant within the critical layer, which moves away from the pipe wall as a result. It is found that the flow stabilizes once the basic profile has become sufficiently fully developed. By tracing the nonlinear neutral curve back to earlier times, it is found that in addition to the wall mode, which arises from a classical upper branch linear stability analysis, there also exists a nonlinear neutral centre mode, governed primarily by inviscid dynamics. The centre mode problem is solved numerically and the results show the existence of a concentrated region of vorticity centred on or close to the pipe axis and propagating downstream at almost the maximum fluid velocity. The connection between this structure and the puffs and slugs of vorticity observed in experiments is discussed.

Station-Keeping Tests of Moored Caisson in Strong Current

2005 ◽  
Vol 127 (4) ◽  
pp. 315-321 ◽  
Author(s):  
Subrata K. Chakrabarti ◽  
Mark McBride
Keyword(s):  
Suspension Bridge ◽  
Mooring Line ◽  
Mooring Lines ◽  
Construction Period ◽  
Physical Model Tests ◽  
Strong Current ◽  
Highly Nonlinear ◽  
Flow Directions ◽  
Flow Interference ◽  
Line Loads

A new suspension bridge is being built over the Tacoma Narrows, Washington. The bridge will be placed on a structure mounted on two large concrete caissons. The caissons are being constructed in a floating position by pouring concrete at site. During this construction period, the floating caissons are moored in place and will be subject to high currents in the Narrows at a range of drafts. In order to investigate the motions of the caisson and the mooring line loads, physical model tests were performed at a scale of 1:100 at HR Wallingford (HRW). The actual bottom contours of the Narrows near the construction site were duplicated in the model. The catenary mooring lines were highly nonlinear. The current forces and moments on the floating caisson included steady and oscillating components due to flow separation and vortex shedding. There is an existing bridge mounted on two piers in the vicinity of the new caissons, which introduced an appreciable flow interference effect. The tests were conducted in both the ebb and flood flow directions so that the effect of the shadowing of the caisson-pier pair could be studied in the tests. The recorded results of the elastic mooring tests were compared in terms of the maximum measured tensions with a time-domain dynamic motion simulation program, MOTSIM. The results of this comparison are presented in this paper.

High-Reynolds-number viscous flow in collapsible tubes

1984 ◽  
Vol 146 ◽  
pp. 451-469 ◽  
Author(s):  
O. R. Tutty
Keyword(s):  
Reynolds Number ◽  
High Reynolds Number ◽  
Fluid Velocity ◽  
Fluid Pressure ◽  
Propagation Speed ◽  
Reynolds Number Flow ◽  
Collapsible Tubes ◽  
Number Flow ◽  
Finite Distance ◽  
High Reynolds

This study is concerned with steady laminar high-Reynolds-number flow in collapsible tubes, where the position of the tube wall is a function (the tube law) only of the pressure exerted by the fluid on the wall. The system is controlled by two main parameters: the Reynolds number of the incoming flow, and the ‘compliance’, which characterizes the response of the wall to a change in fluid pressure. Restrictions are placed on these parameters so that the streamwise lengthscale is large, and, to the order worked, the pressure is uniform across the tube. Attention is restricted to (axi)symmetric systems.Channels are considered in most detail, the results for axisymmetric pipes being largely similar.For a model tube law the flow in the converging section of a channel is investigated in detail. Solutions are presented for certain of the parameter values. For some channels a singularity is found in the solution such that the channel width tends to zero at a finite distance downstream. No way was found to integrate past this singularity.For particular channels and pipes, solutions are found only for flows in which the mean fluid velocity is less than the propagation speed of frictionless waves. This is consistent with experimental results.

Station-Keeping Tests of Moored Caisson in Strong Current

2004 ◽  
Author(s):  
Subrata K. Chakrabarti ◽  
Mark McBride
Keyword(s):  
Suspension Bridge ◽  
Mooring Line ◽  
Mooring Lines ◽  
Construction Period ◽  
Physical Model Tests ◽  
Strong Current ◽  
Highly Nonlinear ◽  
Flow Directions ◽  
Flow Interference ◽  
Line Loads

A new suspension bridge is being built over the Tacoma Narrows, Washington. The bridge will be placed on a structure mounted on two large concrete caissons. The caissons are being constructed in a floating position by pouring concrete at site. During this construction period, the floating caissons are moored in place and will be subject to high currents in the Narrows at a range of drafts. In order to investigate the motions of the caisson and the mooring line loads, physical model tests were performed at a scale of 1:100 at HR Wallingford (HRW). The actual bottom contours of the Narrows near the construction site was duplicated in the model. The catenary mooring lines were highly nonlinear. The current forces and moments on the floating caisson included steady and oscillating components due to flow separation and vortex shedding. There is an existing bridge mounted on two piers in the vicinity of the new caissons, which introduced an appreciable flow interference effect. The tests were conducted in both the ebb and flood flow directions so that the effect of the shadowing of the caisson-pier pair could be studied in the tests. The recorded results of the elastic mooring tests were compared in terms of the maximum measured tensions with a time-domain dynamic motion simulation program, MOTSIM. The results of this comparison are presented in this paper.

Modeling and Simulation of High Reynolds' Number Flows During Reaction Injection Mold Filling

1994 ◽  
Vol 9 (3) ◽  
pp. 279-285 ◽  
Author(s):  
Rahima K. Mohammed ◽  
Tim A. Osswald ◽  
Timothy J. Spiegelhoff ◽  
Esther M. Sun
Keyword(s):  
Reynolds Number ◽  
Modeling And Simulation ◽  
High Reynolds Number ◽  
Mold Filling ◽  
Injection Mold ◽  
High Reynolds ◽  
Reynolds Number Flows
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