Preprint Article Version 1 This version is not peer-reviewed

Unified Friction Formulation from Laminar to Fully Rough Turbulent Flow

Version 1 : Received: 2 October 2018 / Approved: 3 October 2018 / Online: 3 October 2018 (11:38:49 CEST)

A peer-reviewed article of this Preprint also exists.

Brkić, D.; Praks, P. Unified Friction Formulation from Laminar to Fully Rough Turbulent Flow. Appl. Sci. 2018, 8, 2036. Brkić, D.; Praks, P. Unified Friction Formulation from Laminar to Fully Rough Turbulent Flow. Appl. Sci. 2018, 8, 2036.

Journal reference: Applied Sciences 2018, 8, 2036
DOI: 10.3390/app8112036

Abstract

This paper gives a new unified formula for the Newtonian fluids valid for all pipe flow regimes from laminar to the fully rough turbulent. It includes laminar, unstable sharp jump from laminar to turbulent, and all types of the turbulent regimes: smooth turbulent regime, partial non-fully developed turbulent and fully developed rough turbulent regime. The formula follows the inflectional form of curves as suggested in Nikuradse’s experiment rather than monotonic shape proposed by Colebrook and White. The composition of the proposed unified formula consists of switching functions and of the interchangeable formulas for laminar, smooth turbulent and fully rough turbulent flow. The proposed switching functions provide a smooth and a computationally cheap transition among hydraulic regimes. Thus, the here presented formulation represents a coherent hydraulic model suitable for engineering use. The model is compared to existing literature models, and shows smooth and computationally cheap transitions among hydraulic regimes.

Subject Areas

Turbulent flow; Laminar flow; Pipes; Friction factor; Hydraulics; Monotonic roughness, Inflectional roughness; Smooth curve contact; Moody diagram; Hydraulic resistance.

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