Mass or heat transfer to turbulent separated flows for large Schmidt or Prandtl numbers

✍ Scribed by E. Ruckenstein

• Publisher: Elsevier Science
• Year: 1970
• Tongue: English
• Weight: 416 KB
• Volume: 25
• Category: Article
• ISSN: 0009-2509
• DOI: 10.1016/0009-2509(70)85116-8

✦ Synopsis

Equations for the mass transfer (heat transfer) coefficient from a solid surface to turbulent separated flows, near the separation point, are established by means of a physical model proposed previously by the author and also by means of the turbulent diffusion coefficient concept.

In the model method one considers that near the boundary the turbulent motion may be decomposed in a succession of quasilaminar motions each of them taking place along the boundary and having a short path. It is shown that the manner in which the shear stress in the vicinity of the boundary depends on the distance y to the wall affects essentially the manner in which the mass transfer coefficient depends on the diffusion coefficient and on the velocity. A detailed analysis is made for the case in which the shear stress is proportional to the distance y from the wall.

The problem is treated also by means of the turbulent diffusion coefficient concept, an equation for the dependence of this coefficient on the distance y being established. The expression obtained in this manner for the mass transfer coefficient is the same as that deduced by the physical model method.