Laplace pressure

The Laplace pressure is the pressure difference between the inside and the outside of a curved surface that forms the boundary between a gas region and a liquid region. The pressure difference is caused by the surface tension of the interface between liquid and gas.

The Laplace pressure is determined from the Young–Laplace equation given as

where ${\displaystyle R_{1}}$ and ${\displaystyle R_{2}}$ are the principal radii of curvature and ${\displaystyle \gamma }$ (also denoted as ${\displaystyle \sigma }$) is the surface tension. Although signs for these values vary, sign convention usually dictates positive curvature when convex and negative when concave.

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