# Lewis number

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## Lewis number

[′lü·əs ‚nəm·bər]
(physics)
A dimensionless number used in studies of combined heat and mass transfer, equal to the thermal diffusivity divided by the diffusion coefficient. Symbolized Le ; NLe .
Sometimes, the reciprocal of this quantity.
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The set of highly non-linear ordinary differential Equations (14)-(16) with boundary conditions (17)-(18) are solved numerically for the different scale of values of physical emerging parameters such as magnetic field parameter M, electric field [E.sub.1], porosity parameter [lambda], non-linear shrinking sheet parameter n, thermal radiation Rd, Eckert number Ec, Prandtl number Pr, Brownian motion parameter Nb, thermophoresis parameter Nt, Lewis number Le, Velocity slip [delta] and suction parameter s.
In addition, Greg King moved to Billesley from Worcester, while James Tideswell and Rob Lewis number London Welsh among their former homes.
Diffusional-thermal instability is the combined effect of the nonequidiffusive and pure curvature instability and it can be evaluated by the Markstein length ([L.sub.b]) or the Lewis number ([L.sub.e]) .
Figures 15 and 16 elucidate the influences of the thermophoresis parameter, Nt, Brownian motion parameter, Nb, and Lewis number, Le, on the nanoparticle concentration profile for a non-Newtonian fluid.
(4), that as the buoyancy parameter N increases the concentration profiles decrease concentration profiles The heat transfer coefficient as a function of Lewis number Le for varying N , Mn without dispersion ( Pe Pe 0 ) and F0 Pe 0.0 , F0 Pe 1.0 (Darcy can be seen that an increase in the value of the mixed convection and magnetic parameter Mn decreases the heat transfer rate decreases.
where M = 2[sigma][B.sup.2.sub.0]L/c[rho] is the magnetic parameter, Pr = [upsilon]/[alpha] is the Prandtl number, and Le = [upsilon]/[D.sub.B] is the Lewis number. The dimensionless parameters Nb (Brownian motion parameter) and Nt (thermophoresis parameter) are defined as
where Pr is the Prandtl number, Le is the Lewis number, Nb is the Brownian motion parameter, and Nt is the thermophoresis parameter, which are defined as follows:
where the Rayleigh number [Ra.sub.x], the nonlinear temperature parameter [gamma], the buoyancy parameter Nr, the Prandtl number Pr, the Schmidt number Sc, the Peclet number [Pe.sub.x], and the Lewis number Le are defined as
The studied model incorporates the effects of suction injection parameter [alpha], Lewis number Le, the Brownian motion parameter [N.sub.b], and thermophoresis parameter [N.sub.t].
However, the separation rate N is insufficient to describe this dominance, since it is independent of the Lewis number that is the ratio of mass diffusivity and thermal diffusivity, and is a dimensionless characterization of the fluid flows in where there are simultaneous heat and mass transfer by convection.
Finally, to apply the heat and mass transfer analogy to the dehumidifying process, it is necessary to clarify and distinguish the definitions of Lewis number (Le) and Lewis relation ([N.sub.Le]), which are often ambiguously stated in some heat and mass transfer literature.

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