{ "id": "1506.04561", "version": "v1", "published": "2015-06-15T11:55:24.000Z", "updated": "2015-06-15T11:55:24.000Z", "title": "The Euler and Navier-Stokes equations revisited", "authors": [ "Peter Stubbe" ], "comment": "13 pages, no figures", "categories": [ "physics.flu-dyn", "math-ph", "math.MP" ], "abstract": "The present paper is motivated by recent mathematical work on the incompressible Euler and Navier-Stokes equations, partly having physically problematic results and unrealistic expectations. The Euler and Navier-Stokes equations are rederived here from the roots, starting at the kinetic equation for the distribution function in phase space. The derivation shows that the Euler and Navier-Stokes equations are valid only if the fluid under consideration is an ideal gas, and if deviations from equilibrium are small in a defined sense, thereby excluding fully nonlinear solutions. Furthermore, the derivation shows that the Euler and Navier-Stokes equations are unseparably coupled with an appertaining equation for the temperature, whereby, in conjunction with the continuity equation, a closed system of transport equations is set up which leaves no room for any additional equation, with the consequence that the frequently used incompressibility condition $\\nabla\\cdot{\\bf v}=0$ can, at best, be applied to simplify these transport equations, but not to supersede any of them.", "revisions": [ { "version": "v1", "updated": "2015-06-15T11:55:24.000Z" } ], "analyses": { "keywords": [ "navier-stokes equations", "transport equations", "kinetic equation", "incompressibility condition", "distribution function" ], "note": { "typesetting": "TeX", "pages": 13, "language": "en", "license": "arXiv", "status": "editable" } } }