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The irreversible thermodynamic’s theorem of minimum entropy production applied to the laminar and the turbulent Couette flow

  • Analyzing thermodynamic non-equilibrium processes, like the laminar and turbulent fluid flow, the dissipation is a key parameter with a characteristic minimum condition. That is applied to characterize laminar and turbulent behaviour of the Couette flow, including its transition in both directions. The Couette flow is chosen as the only flow form with constant shear stress over the flow profile, being laminar, turbulent or both. The local dissipation defines quantitative and stable criteria for the transition and the existence of turbulence. There are basic results: The Navier Stokes equations cannot describe the experimental flow profiles of the turbulent Couette flow. But they are used to quantify the dissipation of turbulent fluctuation. The dissipation minimum requires turbulent structures reaching maximum macroscopic dimensions, describing turbulence as a “non-local” phenomenon. At the transition the Couette flow profiles and the shear stress change by a factor ≅ 5 due to a change of the “apparent” turbulent viscosity by a calculated factor ≅ 27. The resulting difference of the laminar and the turbulent profiles results in two different Reynolds numbers and different loci of transition, which are identified by calculation.

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Author:Hans Paul Drescher
Document Type:Working Paper
Year of Completion:2018
Publishing Institution:Fachhochschule Aachen
Date of the Publication (Server):2024/04/19
Tag:Minimum dissipation; Transition; Turbulence
Length:48 Seiten
Licence (German):License LogoCreative Commons - Namensnennung