First Laminar Flow Flight Tests Prove Drag Reduction Potential

Abstract By applying a highly water-repellent wall pipe in the drag reduction of polymer solutions, a flow system in which drag reduction is obtained in both laminar and turbulent flow ranges has been realized. Experiments were carried out to measure the pressure drop in pipes with a highly water-repellent wall and an acrylic resin wall by means of a pressure transducer. The diameter of the pipe was 6mm. The polymer solutions tested were PE015 aqueous solutions in the concentration range of 30ppm∼1000ppm. The drag reduction ratio for laminar flow was about 11∼15%. To understand this effect, the pressure drop was measured by using surfactant solutions and degassed water, and by pressurizing tap water in the pipeline. It was shown that the laminar drag reduction does not occur in the case of surfactant solutions although degassed water and pressurizing tap water in the pipeline have no effect on the reduction. In the laminar flow range, the friction factor of a power-law fluid with fluid slip was analyzed by applying the modified boundary condition on fluid slip at the pipe wall, and the analytical results agree with the experimental results in the low Reynolds number range.

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Effect of Superhydrophobic Composite Coatings on Drag Reduction in Laminar Flow

ACS Applied Polymer Materials ◽

10.1021/acsapm.0c00049 ◽

2020 ◽

Vol 2 (4) ◽

pp. 1614-1622 ◽

Cited By ~ 1

Author(s):

Keqin Zheng ◽

Jinde Zhang ◽

Hanna Dodiuk ◽

Samuel Kenig ◽

Carol Barry ◽

...

Keyword(s):

Laminar Flow ◽

Drag Reduction ◽

Composite Coatings

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Drag Reduction using Lubricant-Impregnated Surfaces in Viscous Laminar Flow

Langmuir ◽

10.1021/la5021143 ◽

2014 ◽

Vol 30 (36) ◽

pp. 10970-10976 ◽

Cited By ~ 159

Author(s):

Brian R. Solomon ◽

Karim S. Khalil ◽

Kripa K. Varanasi

Keyword(s):

Laminar Flow ◽

Drag Reduction

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Drag reduction for viscous laminar flow on spray-coated non-wetting surfaces

Soft Matter ◽

10.1039/c3sm50445j ◽

2013 ◽

Vol 9 (24) ◽

pp. 5691 ◽

Cited By ~ 87

Author(s):

Siddarth Srinivasan ◽

Wonjae Choi ◽

Kyoo-Chul Park ◽

Shreerang S. Chhatre ◽

Robert E. Cohen ◽

...

Keyword(s):

Laminar Flow ◽

Drag Reduction

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Numerical Simulation of Fluid Slip at a Hydrophobic Surface

Volume 4 ◽

10.1115/ht-fed2004-56046 ◽

2004 ◽

Author(s):

Takao Fujita ◽

Keizo Watanabe

Keyword(s):

Boundary Condition ◽

Laminar Flow ◽

Circular Cylinder ◽

Drag Reduction ◽

Hydrophobic Surface ◽

Friction Reduction ◽

Water Repellent ◽

Two Dimensional ◽

Hydrophobic Property ◽

Flow Past

Laminar drag reduction is achieved by using a hydrophobic surface. In this method, fluid slip is applied at the hydrophobic surface. An initial experiment to clarify for a laminar skin friction reduction was conducted using ducts with a highly water-repellent surface. The surface has a fractal-type structure with many fine grooves. Fluid slip at a hydrophobic surface has been analyzed by applying a new wet boundary condition. In this simulation, an internal flow is assumed to be a two-dimensional laminar flow in a rectangular duct and an external flow is assumed to be a two-dimensional laminar flow past a circular cylinder. The VOF technique has been used as the method for tracking gas-liquid interfaces, and the CSF model has been used as the method for modeling surface tension effects. The wet boundary condition for the hydrophobic property on the surface has been determined from the volume ratio in contact with water near the surface. The model with a stable gas-liquid interface and the experimental results of flow past a circular cylinder at Re = 250 without growing the Karman vortex street are made, and these results show that laminar drag reduction occurring due to fluid slip can be explained in this model.

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Laminar Flow Past a Circular Cylinder: Reduction of Drag and Fluctuating Lift Using Upstream and Downstream Rods

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.493.9 ◽

2014 ◽

Vol 493 ◽

pp. 9-14

Author(s):

Dedy Zulhidayat Noor ◽

Eddy Widiyono ◽

Suhariyanto ◽

Lisa Rusdiyana ◽

Joko Sarsetiyanto

Keyword(s):

Reynolds Number ◽

Laminar Flow ◽

Circular Cylinder ◽

Drag Reduction ◽

Passive Control ◽

Low Reynolds Number ◽

Tandem Arrangement ◽

Single Cylinder ◽

Flow Past ◽

Low Reynolds

Laminar flow past a circular cylinder has been studied numerically at low Reynolds number. The upstream and downstream rods have been used as passive control in order to reduce hydrodynamics forces acting on the cylinder. Both the upstream and downstream rods significantly contribute in reduction of drag and fluctuating lift compared to single cylinder without the rods. More detail, the upstream installation rod is more dominant in drag reduction than the downstream one. On the contrary, the downstream rod has suppressed the magnitude of the fluctuating lift almost twice that of the upstream configuration. Placing the two rods together as the upstream and downstream passive control in tandem arrangement has given more hydrodynamics forces reduction than the single rod configurations.Keywords:circular cylinder, passive control, tandem, drag, lift.

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