Lewis number

(Difference between revisions)

Latest revision as of 09:55, 17 December 2008

The Lewis number for a given species $k$ is

$Le_k \equiv \frac{\lambda}{\rho C_p D_k}$

Denoting $D_{th}= \lambda / \rho C_p$ the heat diffusivity coefficient the Lewis number can be expressed as

$Le_k \equiv \frac{D_{th}}{ D_k}$

which is the ratio of the heat diffusion speed to the diffusion speed of species $k$ .

In many combustion models, all species are assumed to diffuse at the same speed and therefore $Le = 1$

@@ Line 6: / Line 6: @@
 can be expressed as
 :<math>
-Le_k = \frac{D_{th}}{ D_k}
+Le_k \equiv \frac{D_{th}}{ D_k}
 </math>
 which is the ratio of the heat diffusion speed to the diffusion speed of species <math> k </math>.
 In many combustion models, all species are assumed to diffuse at the same speed and therefore
-<math> Le \equiv 1 </math>
+<math> Le = 1 </math>
 [[Category:Dimensionless parameters]]