An Experimental Study of Drag Reduction in a Pipe with Superhydrophobic Coating at Moderate Reynolds Numbers

Chen, J.H.; Tsai, Chia-Jung; Kehr, Young-Zehr; Horng, Lance; Chang, Kelken; Kuo, Li‐Yaung

doi:10.1051/epjconf/20100619005

Cited by 8 publications

(4 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A few others investigated this effect in curved pipes 5,18,19 . Other methods of drag reduction involving pipe modifications such as riblets, dimples, wavering walls, and amenable surfaces are also common 20‐23 …”

Section: Introductionmentioning

confidence: 99%

A review of drag reduction by additives in curved pipes for single‐phase liquid and two‐phase flows

Ayegba

Edomwonyi‐Otu

Yusuf

et al. 2020

Engineering Reports

View full text Add to dashboard Cite

The effect of drag‐reducing agents (DRAs) on fluid flows in straight pipes has been well documented. Key among these is the effect of DRAs on turbulence statistics (Reynolds shear stress, turbulence intensity, streamwise and wall‐normal velocity fluctuation among others). These primary effects result in secondary effects such as modification of mean velocity profile and reduction in frictional losses (drag reduction, DR). Interestingly, in curved pipe flows, the characteristic of flow is more complex due to secondary flow, wake effects and under‐developed flow characteristics. Therefore, a review of investigations on the effect of DRAs in curved pipe flows is presented in this paper. The paper highlights the difference between DR in straight and curved conduits as well as the interaction between DRAs and flow characteristics of curved pipe flows. Proposed mechanisms of DR, and factors that influence their effectiveness also received attention. It was shown that significant DR can be achieved in curved pipes. A review of various experimental results revealed that DR by additives in curved pipes is generally lower than in straight pipes but with certain similarities. It decreases with increase in curvature ratio and is more pronounced in the transition and turbulent flow regimes. Maximum DR asymptote differed between straight and curved pipes and between polymer and surfactant. Due to the limited studies in the area of DR for gas‐liquid flow in curved pipes, no definite conclusion could be drawn on the effect of DRAs on such flows. A number of questions remain such as physical interaction between molecules of DRA and flow features such as secondary flow streamlines and wakes. Hence, some research gaps have been identified with recommendations for areas of future researches.

show abstract

Section: Introductionmentioning

confidence: 99%

A review of drag reduction by additives in curved pipes for single‐phase liquid and two‐phase flows

Ayegba

Edomwonyi‐Otu

Yusuf

et al. 2020

Engineering Reports

View full text Add to dashboard Cite

show abstract

“…Their findings stirred great interest in hydrophobicity research [6], and since then this area has attracted increasing attention due to its wide range of applications in the automobile, aerospace, nautical, plumbing, and biomedical industries for functions such as hydrophobic surface corrosion resistance, rust prevention, friction reduction, and the improvement of cell adhesion [7][8][9][10][11][12]. In the hydrophobic realm, automobiles and aircraft can have self-cleaning and anti-frosting properties, and medical implants can prevent blood coagulation and reduce the incidence of diseases like stent thrombosis [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Superhydrophobic Surfaces Enabled by Femtosecond Fiber Laser-Written Nanostructures

Liu

Lee

2020

Applied Sciences

View full text Add to dashboard Cite

Inspired by the self-cleaning and water-repellent lotus leaf, we have developed an efficient process to create superhydrophobic metal surfaces using a femtosecond fiber laser and have investigated the mechanisms of the structured metal surfaces in relation to their hydrophobicity. The at will feature of femtosecond fiber lasers can write versatile patterns of hydrophobicity with nanoscale precision on any metal. The results show that the homogeneously distributed hierarchical structures exhibit multifunctional properties, including superhydrophobicity, self-cleaning, and light-trapping. By optimizing the fabrication conditions, we have achieved a contact angle as high as 171° and a rolling angle of less than 3°. The structure is also resistant to an extreme temperature range of −40 °C to 71 °C and temperature shocks from 20 °C to −40 °C. This research highlights the exciting potential applications of superhydrophobic metals in the aviation, biomedical, and solar energy industries and beyond.

show abstract

“…A few others investigated this effect in curved pipes [9][10][11]. Other methods of drag reduction involving pipe modifications such as riblets, dimples, wavering walls and amenable surfaces are also common [12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Drag Reduction by Additives in Curved Pipes for Single-Phase Liquid and Two-Phase Flows: A Review

Ayegba¹,

Edomwonyi‐Otu²,

Abubakar³

et al. 2020

Preprint

View full text Add to dashboard Cite

A review of influence of drag-reducing agents on curved pipe flows is presented in this work. In addition, this review outlined proposed mechanism, friction factor and fluid flux models for drag-reducing agents in curved pipe flows. Our finding reveals that drag reduction by additives in curved pipes is quite significant but generally lower than the corresponding drag reduction in straight pipes. It decreases with increase in curvature ratio and more pronounced in the transition and turbulent flow regimes. Drag reduction strongly depends on the polymers and surfactants' concentrations as well as the bubble fraction of micro-bubbles. It is also reported that drag reduction in curved pipes depends on temperature and existence of dissolved salts in the fluids. Maximum drag reduction asymptote differed between straight and curved pipes and between polymer and surfactant. No definite conclusion could be drawn as regards drag reduction for two-phase flow in curved pipes due to the limited studies in this area. Many questions such as the mechanism of drag reduction in curved pipes and how drag-reducing agents interact with secondary flows still remained unanswered. Hence, some research gaps have been identified with recommendations for areas of future researches.

show abstract

An Experimental Study of Drag Reduction in a Pipe with Superhydrophobic Coating at Moderate Reynolds Numbers

Cited by 8 publications

References 17 publications

A review of drag reduction by additives in curved pipes for single‐phase liquid and two‐phase flows

A review of drag reduction by additives in curved pipes for single‐phase liquid and two‐phase flows

Superhydrophobic Surfaces Enabled by Femtosecond Fiber Laser-Written Nanostructures

Drag Reduction by Additives in Curved Pipes for Single-Phase Liquid and Two-Phase Flows: A Review

Contact Info

Product

Resources

About