New developments in surface roughness measurements, characterization, and modeling fluid flow in pipe

Farshad, Fred F.; Rieke, Herman H.; Garber, James D.

doi:10.1016/s0920-4105(01)00096-1

Cited by 41 publications

(25 citation statements)

References 6 publications

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“…From literature values and our case, ( Figure S3, Supporting Information), we find R q ≈ 1.1−1.3 R a . 46,50 The advantage of AFM is that it can obtain the surface roughness at nanometer scale without damaging the samples. However, the disadvantage of our apparatus (dimension 3100 AFM) is that the scanning area is limited up to 50 × 50 μm.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Influence of Packing Density and Surface Roughness of Vertically-Aligned Carbon Nanotubes on Adhesive Properties of Gecko-Inspired Mimetics

Chen

Zhong

Oppenheimer

et al. 2015

ACS Appl. Mater. Interfaces

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ABSTRACT:We have systematically studied the macroscopic adhesive properties of vertically aligned nanotube arrays with various packing density and roughness. Using a tensile setup in shear and normal adhesion, we find that there exists a maximum packing density for nanotube arrays to have adhesive properties. Too highly packed tubes do not offer intertube space for tube bending and side-wall contact to surfaces, thus exhibiting no adhesive properties. Likewise, we also show that the surface roughness of the arrays strongly influences the adhesion properties and the reusability of the tubes. Increasing the surface roughness of the array strengthens the adhesion in the normal direction, but weakens it in the shear direction. Altogether, these results allow progress toward mimicking the gecko's vertical mobility.

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Section: ■ Experimental Sectionmentioning

confidence: 99%

Influence of Packing Density and Surface Roughness of Vertically-Aligned Carbon Nanotubes on Adhesive Properties of Gecko-Inspired Mimetics

Chen

Zhong

Oppenheimer

et al. 2015

ACS Appl. Mater. Interfaces

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“…The absolute roughness divided by the internal diameter gives the relative roughness of the pipe, with the pipe considered smooth when the projections of the surface are completely submerged in the viscous laminar layer (Farshad et al, 2001). The Colebrook-White equation (Colebrook, 1939;Colebrook and White, 1937) (Equation (1)) has become the accepted standard for calculating the friction factor in pipes, given its applicability over a wide range of flow regimes and relative pipe roughness values.…”

Section: Introductionmentioning

confidence: 99%

Improved method of determining friction factor in pipes

Winning¹,

Coole

2015

International Journal of Numerical Methods for Heat &Amp; Fluid Flow

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Purpose -The purpose of this paper is to present an improved computational method for determining the friction factor for turbulent flow in pipes. Design/methodology/approach -Given that the absolute pipe roughness is generally constant in most systems, and that there are few changes to the pipe diameter, the proposed method uses a simplified equation for systems with a specific relative pipe roughness. The accuracy of the estimation of the friction factor using the proposed method is compared to the values obtained using the implicit Colebrook-White equation while the computational efficiency is determined by comparing the time taken to perform 300 million calculations. Findings -The proposed method offers a significant improvement in computational efficiency for its accuracy and is compared 28 of the explicit equations currently in use. Practical implications -This method enables a simplified equation to offer a significant improvement in computational efficiency for its accuracy and is easier to code, enabling engineers to more efficiently calculate frictional pressure loss for flow in pipes. Originality/value -Due to the complexities in flow regime and pipe roughness, there is a limit to the scope for further computational efficiency through simplification of the explicit equation. This paper presents a new method and simplified equation which combined are able to deliver results with similar accuracy to less computationally efficient explicit equations.

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“…The bigger problem is how to measure or estimate the value of roughness accurately (Sletfjerding and Gudmundsson, 2003;Farshad et al, 2001). Li et al (2011) have examined few equations valid for the "smooth" turbulent regime such as Blasius, Filonenko, etc (Table 1).…”

Section: Figure 2 Examined Hydraulic Problemmentioning

confidence: 99%

Can pipes be actually really that smooth?

Brkić¹

2012

International Journal of Refrigeration

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New developments in surface roughness measurements, characterization, and modeling fluid flow in pipe

Cited by 41 publications

References 6 publications

Influence of Packing Density and Surface Roughness of Vertically-Aligned Carbon Nanotubes on Adhesive Properties of Gecko-Inspired Mimetics

Influence of Packing Density and Surface Roughness of Vertically-Aligned Carbon Nanotubes on Adhesive Properties of Gecko-Inspired Mimetics

Improved method of determining friction factor in pipes

Can pipes be actually really that smooth?

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