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Turbulence model sensitivity and scour gap effect of unsteady flow around pipe: a CFD study.

Ali A, Sharma RK, Ganesan P, Akib S - ScientificWorldJournal (2014)

Bottom Line: A numerical investigation of incompressible and transient flow around circular pipe has been carried out at different five gap phases.Flow equations such as Navier-Stokes and continuity equations have been solved using finite volume method.Unsteady horizontal velocity and kinetic energy square root profiles are plotted using different turbulence models and their sensitivity is checked against published experimental results.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia.

ABSTRACT
A numerical investigation of incompressible and transient flow around circular pipe has been carried out at different five gap phases. Flow equations such as Navier-Stokes and continuity equations have been solved using finite volume method. Unsteady horizontal velocity and kinetic energy square root profiles are plotted using different turbulence models and their sensitivity is checked against published experimental results. Flow parameters such as horizontal velocity under pipe, pressure coefficient, wall shear stress, drag coefficient, and lift coefficient are studied and presented graphically to investigate the flow behavior around an immovable pipe and scoured bed.

Show MeSH
Effect on (a) drag coefficient (Cd) and lift coefficient (Cl) at cylinder surface of different time phases.
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Related In: Results  -  Collection


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fig10: Effect on (a) drag coefficient (Cd) and lift coefficient (Cl) at cylinder surface of different time phases.

Mentions: When the flow approaches the pipe, it imparts drag and lift forces on the pipe. In the current numerical study, variations in these forces are observed in terms of drag and lift coefficients for five different time phases and presented in Figure 10. Shear stress causes the bed erosion and as soon as it comes into action, the pipe experiences negative lift coefficient (Cl) and it decreases with time and consequently increases the scour gap. The negative lift can be attributed to the suction below and behind the pipe caused by the scour gap. For velocity, negative lift can be explained by the position of the stagnation point pipe and the angle of attack of the approaching flow. As a result of lift coefficient elimination, the drag coefficient is reduced with time as well. A reduction of 23.7% in Cd and 51.3% in Cl was observed between the time phases of 10 min and 300 min.


Turbulence model sensitivity and scour gap effect of unsteady flow around pipe: a CFD study.

Ali A, Sharma RK, Ganesan P, Akib S - ScientificWorldJournal (2014)

Effect on (a) drag coefficient (Cd) and lift coefficient (Cl) at cylinder surface of different time phases.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4129154&req=5

fig10: Effect on (a) drag coefficient (Cd) and lift coefficient (Cl) at cylinder surface of different time phases.
Mentions: When the flow approaches the pipe, it imparts drag and lift forces on the pipe. In the current numerical study, variations in these forces are observed in terms of drag and lift coefficients for five different time phases and presented in Figure 10. Shear stress causes the bed erosion and as soon as it comes into action, the pipe experiences negative lift coefficient (Cl) and it decreases with time and consequently increases the scour gap. The negative lift can be attributed to the suction below and behind the pipe caused by the scour gap. For velocity, negative lift can be explained by the position of the stagnation point pipe and the angle of attack of the approaching flow. As a result of lift coefficient elimination, the drag coefficient is reduced with time as well. A reduction of 23.7% in Cd and 51.3% in Cl was observed between the time phases of 10 min and 300 min.

Bottom Line: A numerical investigation of incompressible and transient flow around circular pipe has been carried out at different five gap phases.Flow equations such as Navier-Stokes and continuity equations have been solved using finite volume method.Unsteady horizontal velocity and kinetic energy square root profiles are plotted using different turbulence models and their sensitivity is checked against published experimental results.

View Article: PubMed Central - PubMed

Affiliation: Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia.

ABSTRACT
A numerical investigation of incompressible and transient flow around circular pipe has been carried out at different five gap phases. Flow equations such as Navier-Stokes and continuity equations have been solved using finite volume method. Unsteady horizontal velocity and kinetic energy square root profiles are plotted using different turbulence models and their sensitivity is checked against published experimental results. Flow parameters such as horizontal velocity under pipe, pressure coefficient, wall shear stress, drag coefficient, and lift coefficient are studied and presented graphically to investigate the flow behavior around an immovable pipe and scoured bed.

Show MeSH