Continuum flow
A flowing medium is in the state of continuum flow (also viscous flow ) when the medium can be roughly understood as a continuum . If this is the case, the mathematical description of the flow does not have to consider every single molecule ( microscopic model / molecular flow ); instead, continuum mechanics can be used (macroscopic model). The macroscopic quantities such as pressure, temperature and density are then mean values of the microscopic quantities such as momentum, energy and mass. A flow in the continuum area can be described with the help of the Navier-Stokes equations .
Gases are in the state of continuum flow when the Knudsen number is significantly smaller than one ( ), i.e. the mean free path is significantly shorter than a characteristic length L of the body under consideration.
literature
- Arnold Sommerfeld : Mechanics of deformable media (= lectures on theoretical physics. Vol. 2). Akademische Verlagsgesellschaft Becker & Erler, Leipzig 1945, (reprint of the 6th edition, edited and supplemented by Erwin Fues and Ekkehart Kröner . Harri Deutsch, Thun et al. 1992, ISBN 3-87144-375-1 ).