Eddy diffusion

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Under eddy diffusion or Eddy dispersion (in English also turbulent diffusion or scattering diffusion ) is the process by which substances in the atmosphere or any fluidem system by vortex mixing motion.

Chromatography

In chromatography , Eddy diffusion describes the first part of the Van Deemter equation . It contributes to band broadening due to uneven substance migration within a column packed with particles of different size. The sample molecules do not migrate linearly, but rather “zigzag” on different paths through the separation bed. The contribution of the eddy diffusion is independent of the linear flow velocity of the mobile phase .

Fluid mechanics

In fluid mechanics , eddy diffusion is understood as the spread or distribution of a substance in a flowing fluid through turbulent mixing. In contrast to molecular diffusion , vortex diffusion is much faster. An illustrative example is a cup of coffee with a lump of sugar. Even if the sugar dissolves relatively quickly, it will take hours to days for the sugar to diffuse into the cup. Stirring once does the same by swirling in seconds.

Individual evidence

  1. ↑ M. Otto: Analytical Chemistry . 3. Edition. WILEY-VCH, 2006, ISBN 978-3-527-31416-4 , pp. 443 .
  2. ↑ a b Gey: Instrumental and analytics and bioanalysis . 2nd Edition. Springer, 2008, ISBN 978-3-540-73803-9 , pp. 95 , doi : 10.1007 / 978-3-540-73804-6 .
  3. ↑ a b Schwedt: Analytical Chemistry . 2nd Edition. WILEY-VCH, 2008, ISBN 978-3-527-31206-1 , pp. 385 .
  4. ↑ Entry on eddy dispersion (diffusion) . In: IUPAC Compendium of Chemical Terminology (the “Gold Book”) . doi : 10.1351 / goldbook.E01889 Version: 2.1.5.
  5. ↑ Geophysical Fluid Dynamics Lectures: Eddy Diffusion (in English; PDF; 2.4 MB)

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