Del - Notational Uses - Directional Derivative

Directional Derivative

The directional derivative of a scalar field f(x,y,z) in the direction is defined as:

This gives the change of a field f in the direction of a. In operator notation, the element in parentheses can be considered a single coherent unit; fluid dynamics uses this convention extensively, terming it the convective derivative—the "moving" derivative of the fluid.

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