Turbulent flow in a machine honed rough pipe for large Reynolds numbers: General roughness scaling laws

Afzal, Noor; Seena, Abu; Bushra, A.

doi:10.1016/j.jher.2011.08.002

Cited by 17 publications

(14 citation statements)

References 21 publications

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“…The roughness equivalent to the sand grain originally defined in the studies of Johann Nikuradse (Hager & Liiv, 2008;Yang & Jooseph, 2009) was satisfactorily correlated with the parameters Ra, Rq and Rc by Afzal et al (2013), evaluating turbulent flow in rough pipes. Figure 3 shows the analysis of frequency distribution of relative errors of the head loss estimates adopting the best roughness parameter, identified by the ranking in Table 3.…”

Section: Methodsmentioning

confidence: 88%

Internal surface roughness of plastic pipes for irrigation

Rocha

Marques

Camargo

et al. 2017

Rev. bras. eng. agríc. ambient.

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A B S T R A C TAssuming that a roughness meter can be successfully employed to measure the roughness on the internal surface of irrigation pipes, this research had the purpose of defining parameters and procedures required to represent the internal surface roughness of plastic pipes used in irrigation. In 2013, the roughness parameter Ra, traditional for the representation of surface irregularities in most situations, and the parameters Rc, Rq, and Ry were estimated based on 350 samples of polyvinyl chloride (PVC) and low-density polyethylene (LDPE) pipes. Pressure losses were determined from experiments carried out in laboratory. Estimations of pressure loss varied significantly according to the roughness parameters (Ra, Rc, Rq, and Ry) and the corresponding pipe diameter. Therefore, specific values of roughness for each pipe diameter improves accuracy in pressure losses estimation. The average values of internal surface roughness were 3.334 and 8.116 µm for PVC and LDPE pipes, respectively. Rugosidade interna de tubos plásticos utilizados em irrigação R E S U M OObjetivou-se, no presente estudo, estabelecer os parâmetros de amplitude das irregularidades da superfície interna de tubos plásticos para irrigação, assim como procedimentos para sua obtenção e representação utilizando-se um rugosímetro de bancada. Durante o ano de 2013 foram avaliados 350 perfis de rugosidade de tubos de PVC e polietileno de baixa densidade (PEBDL), sendo determinados os parâmetros de rugosidade Ra, clássico para a representação das irregularidades de superfícies na maioria das situações, além dos parâmetros adicionais Rc, Rq e Ry. Determinações hidráulicas de perda de carga foram realizadas em laboratório para comparação com a perda de carga obtida pela aplicação dos parâmetros de rugosidade. Evidenciou-se diferença significativa de desempenho estatístico dos parâmetros de rugosidade (Ra, Rq, Rc e Ry) de acordo com o diâmetro do tubo e, portanto, constatou-se que a adoção de valores de rugosidade específicos para cada diâmetro contribui para a exatidão das estimativas de perda de carga. A rugosidade média para tubos de PVC e PEBDL foi 3,334 e 8,116 µm, respectivamente.

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Section: Methodsmentioning

confidence: 88%

Internal surface roughness of plastic pipes for irrigation

Rocha

Marques

Camargo

et al. 2017

Rev. bras. eng. agríc. ambient.

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“…In order to close the system of equations (34) and (35), it is necessary to define the Darcy friction factor f D or at least to express it in terms of the state space variables y 1 , y 2 ,ẏ 1 andẏ 2 , which is the critical step in classical approaches. In general, either one additional hypothesis is assumed (for example laminar regime), carry out simulations with complex fluid flow models or use a semi-empirical equation such as Kármán -Prandtl resistance equation for the smooth turbulent regime, [46], [47], the well-known Colebrook-White equation [48] or other more recent equations for the transition from a smooth pipe to a rough pipe flow [49], [50], [51]. One way or another, these approaches complete the physics based on the particular hypothesis stated a priori.…”

Section: Standard Data-science Problemmentioning

confidence: 99%

An unsupervised data completion method for physically-based data-driven models

Ayensa-Jiménez

Doweidar

Sanz-Herrera

et al. 2019

Computer Methods in Applied Mechanics and Engineering

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Data-driven methods are an innovative model-free approach for engineering and sciences, still in process of maturation. The idea behind is the combination of data analytics techniques, to handle the huge amount of data derived from continuous monitoring or experimental measurements, and of the constraints imposed by universal physical laws, particular to the field in hands. A well-known problem in the former corresponds to the quality and completeness of the available data that, sometimes, are so poor that make the predictions useless. In

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“…The lateral and top boundary conditions were defined as frictionless walls following the best practice guidelines [13,14] and a constant static pressure condition was prescribed at the outlet. Standard wall law [59] was used for the floor and the different buildings walls.…”

Section: Computational Settingsmentioning

confidence: 99%

Wind comfort assessment by means of large eddy simulation with lattice Boltzmann method in full scale city area

Jacob

Sagaut

2018

Building and Environment

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Large-eddy simulations based on the Lattice-Boltzmann method of the flow in a realistic, full scale urban area are performed to compare several wind comfort criteria. It is observed that popular criteria for pedestrian comfort lead to very different conclusions, due to the access to high spatio-temporal resolution data. Different mixed strategies based on the combination of several criteria are proposed and compared to enhance pedestrian wind comfort assessment in practical cases.

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Turbulent flow in a machine honed rough pipe for large Reynolds numbers: General roughness scaling laws

Cited by 17 publications

References 21 publications

Internal surface roughness of plastic pipes for irrigation

Internal surface roughness of plastic pipes for irrigation

An unsupervised data completion method for physically-based data-driven models

Wind comfort assessment by means of large eddy simulation with lattice Boltzmann method in full scale city area

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