https://www.scipedia.com/wd/index.php?action=history&feed=atom&title=Praks_Brkic_2018aPraks Brkic 2018a - Revision history2026-04-26T01:19:53ZRevision history for this page on the wikiMediaWiki 1.27.0-wmf.10https://www.scipedia.com/wd/index.php?title=Praks_Brkic_2018a&diff=163248&oldid=prevDejan.brkic: Dejan.brkic moved page Draft Brkic 973539986 to Praks Brkic 2018a2020-05-16T12:25:05Z<p>Dejan.brkic moved page <a href="/public/Draft_Brkic_973539986" class="mw-redirect" title="Draft Brkic 973539986">Draft Brkic 973539986</a> to <a href="/public/Praks_Brkic_2018a" title="Praks Brkic 2018a">Praks Brkic 2018a</a></p>
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</td></tr></table>Dejan.brkichttps://www.scipedia.com/wd/index.php?title=Praks_Brkic_2018a&diff=163247&oldid=prevDejan.brkic: Created page with " == Abstract == idely used in hydraulics, the Colebrook equation for flow friction relates implicitly to the input parameters; the Reynolds number, Re and the relative roughn..."2020-05-16T12:25:03Z<p>Created page with " == Abstract == idely used in hydraulics, the Colebrook equation for flow friction relates implicitly to the input parameters; the Reynolds number, Re and the relative roughn..."</p>
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== Abstract ==<br />
<br />
idely used in hydraulics, the Colebrook equation for flow friction relates implicitly to the input parameters; the Reynolds number, Re and the relative roughness of an inner pipe surface, ε/D with an unknown output parameter; the flow friction factor, λ; λ = f (λ, Re, ε/D). In this paper, a few explicit approximations to the Colebrook equation; λ≈f (Re, ε/D), are generated using the ability of artificial intelligence to make inner patterns to connect input and output parameters in an explicit way not knowing their nature or the physical law that connects them, but only knowing raw numbers, {Re, ε/D}→{λ}. The fact that the used genetic programming tool does not know the structure of the Colebrook equation, which is based on computationally expensive logarithmic law, is used to obtain a better structure of the approximations, which is less demanding for calculation but also enough accurate. All generated approximations have low computational cost because they contain a limited number of logarithmic forms used for normalization of input parameters or for acceleration, but they are also sufficiently accurate. The relative error regarding the friction factor λ, in in the best case is up to 0.13% with only two logarithmic forms used. As the second logarithm can be accurately approximated by the Padé approximation, practically the same error is obtained also using only one logarithm.<br />
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== Full document ==<br />
<pdf>Media:Draft_Brkic_973539986-2653-document.pdf</pdf></div>Dejan.brkic