Lewis number
Physical key figure | |||||
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Surname | Lewis number | ||||
Formula symbol | |||||
dimension | dimensionless | ||||
definition | |||||
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Named after | Warren Lewis | ||||
scope of application | thermal diffusion |
The Lewis number (after Warren Lewis ) is a dimensionless number in physics .
In the case of heat and mass transfer , it represents the ratio of heat conduction to diffusion , expressed as the quotient of thermal diffusivity and diffusion coefficient
The Lewis number relates the thickness of the thermal boundary layer to the concentration boundary layer. According to the above equation, the thermal diffusivity can be calculated from the thermal conductivity , the isobaric specific heat capacity and the density of the fluid .
By expanding the dynamic viscosity , the Lewis number can also be represented as the quotient of the Schmidt number and the Prandtl number :
Individual evidence
- ^ WK Lewis: The Evaporation of a Liquid Into a Gas In: Transactions of the American Society of Mechanical Engineers , No. 1849, 1922, pp. 325-340.
- ^ A. Klinkenberg, HH Mooy: Dimensionless Groups in Fluid Friction, Heat, and Material Transfer In: Chemical Engineering Progress , Volume 44, No. 1, 1948, pp. 17-36.
- ^ Josef Kunes: Dimensionless Physical Quantities in Science and Engineering . Elsevier, 2012, ISBN 0-12-391458-2 , pp. 254 ( limited preview in Google Book search).
- ↑ tec-science: Lewis number. In: tec-science. May 9, 2020, accessed on June 25, 2020 (German).