What purpose does the delta notation serve in this context?

[Steven_Scott]

In a book on atmospheric physics I'm reading, the author begins a derivation by examining a fluid element of volume V = δxδyδz.

In this context, what purpose is delta δ serving? Is it just a placeholder for an unspecified volume in the x, y, and z directions, or is it referring to an infinitesimal volumetric quantity?

 

[RPinPA]

The words "fluid element" tells me this is a thing which is going to be integrated. So yes, I think it will shortly be replaced by an infinitesimal quantity in the derivation.

 

[Mister T]

In a book on atmospheric physics I'm reading, the author begins a derivation by examining a fluid element of volume V = δxδyδz.

In this context, what purpose is delta δ serving? Is it just a placeholder for an unspecified volume in the x, y, and z directions, or is it referring to an infinitesimal volumetric quantity?

Each volume element is a cube that measures δx by δy by δz. For example, the left edge of one of these cubes might have a position x = 1.5 and the position of the right edge is x = 1.6. Then δx=0.1.