Law of Young-Dupre

See also: Dupre

The law of Young-Dupre gives the expression of the static Contact angle of a liquid drop deposited on a solid substrate, in balance with a vapor phase:

$\backslash \; cos\; \backslash \; theta=\; \backslash \; frac\; \{\backslash \; gamma\_\; \{SV\}\; -\; \backslash \; gamma\_\; \{SSL\}\}\; \{\backslash \; gamma\_\; \{LV\}\}$

where:

$\backslash \; gamma\_\; \{SV\}$, $\backslash \; gamma\_\; \{SSL\}$ and $\backslash \; gamma\_\; \{LV\}$ indicates the surface Tension respectively interfaces solid/vapor, solid/liquid and liquid/vapor.

Partial or total damping

When $-1\; \backslash \; Leq\; \backslash \; frac\; \{\backslash \; gamma\_\; \{SV\}\; -\; \backslash \; gamma\_\; \{SSL\}\}\; \{\backslash \; gamma\_\; \{LV\}\}\; \backslash \; leq1$, the contact angle is defined by the relation of Young-Dupre. That corresponds to a situation of partial damping .

The case $\backslash \; frac\; \{\backslash \; gamma\_\; \{SV\}\; -\; \backslash \; gamma\_\; \{SSL\}\}\; \{\backslash \; gamma\_\; \{LV\}\}\; \backslash \; geq\; 1$ corresponds to a situation of total damping where the solid substrate is covered with a film of liquid which extends on all solid surface available. The solid interface/vapor then disappeared.

Finally the case $\backslash \; frac\; \{\backslash \; gamma\_\; \{SV\}\; -\; \backslash \; gamma\_\; \{SSL\}\}\; \{\backslash \; gamma\_\; \{LV\}\}\; \backslash \; Leq\; -1$ is symmetrical precedent: the solid is covered with a vapor film and the solid interface/liquid disappears. With the limit where $\backslash \; gamma\_\; \{SV\}\; -\; \backslash \; gamma\_\; \{SSL\}\; =\; \backslash \; gamma\_\; \{LV\}$, one has a situation of null damping .

Category: Mechanics of the nonhomogeneous mediums Category: Law in physics

Random links:

Kati | A marvellous day | Vianos | The Factory | County of Greene (Pennsylvania) | Belle,_Missouri

© 2007-2008 speedlook.com; article text available under the terms of GFDL, from fr.wikipedia.org