ThermodynamicsのA-Zガイド、熱&アンプ、質量移動、流体工学
English Русский 中文 Português Español Français Deutsch 概要 編集委員会 連絡先 アクセス Begell House
View in Semantic Map View in A-Z Index

A Newtonian fluid is one where there is a linear relationship between stress and strain-rate. The ratio of stress to strain-rate is the Viscosity of the fluid. A fluid where there is no linear relationship between stress and strain-rate is called a Non-Newtonian fluid.

For a Newtonian fluid the stress (strictly, the deviatoric stress) τ is given by:

(1)

where e denotes the strain-rate given in terms of the velocity u by:

(2)

and η denotes the viscosity of the fluid, which is independent of e, though it may depend on temperature T and perhaps on pressure p.

Because e is a symmetrical tensor, it follows from (1) that t too is a symmetrical tensor:

(3)

Angular momentum conservation then implies that Newtonian fluids are nonpolar and hence, that the angular momentum is just the moment of the linear momentum.

Most fluids under normal circumstances are Newtonian so the study of Newtonian fluids comprises the major part of the subject of fluid mechanics. Linear momentum conservation then leads to the Navier-Stokes equations.

表示回数: 37605 記事追加日: 2 February 2011 記事最終修正日: 16 March 2011 ©著作権 2010-2022 トップへ戻る
A-Z索引 著者/編集者 意味マップ ビジュアルギャラリー 寄稿 Guest