{ "id": "1610.03468", "version": "v1", "published": "2016-10-11T19:03:43.000Z", "updated": "2016-10-11T19:03:43.000Z", "title": "Algebraic proof and application of Lumley's realizability triangle", "authors": [ "G. A. Gerolymos", "I. Vallet" ], "categories": [ "physics.flu-dyn" ], "abstract": "Lumley [Lumley J.L.: Adv. Appl. Mech. 18 (1978) 123--176] provided a geometrical proof that any Reynolds-stress tensor $\\overline{u_i'u_j'}$ (indeed any tensor whose eigenvalues are invariably nonnegative) should remain inside the so-called Lumley's realizability triangle. An alternative formal algebraic proof is given that the anisotropy invariants of any positive-definite symmetric Cartesian rank-2 tensor in the 3-D Euclidian space $\\mathbb{E}^3$ define a point which lies within the realizability triangle. This general result applies therefore not only to $\\overline{u_i'u_j'}$ but also to many other tensors that appear in the analysis and modeling of turbulent flows. Typical examples are presented based on DNS data for plane channel flow.", "revisions": [ { "version": "v1", "updated": "2016-10-11T19:03:43.000Z" } ], "analyses": { "keywords": [ "lumleys realizability triangle", "application", "general result applies", "positive-definite symmetric cartesian", "alternative formal algebraic proof" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable" } } }