flux

quantity per unit time per unit area, quantity/(time*area)

(no term)

Quantities that can be fluxed in fluids include fluid mass, momentum, energy, etc.

There are three fundamental mechanisms of flux of interest in fluid mechanics:

• convective flux
• diffusive flux
• radiative flux
• the quantity is carried with the flow
• the quantity migrates from zones of high concentration to zones of low concentration by random molecular motion
• the quantity (e.g. heat) is carried by waves such as electromagnetic waves (in the infrared spectrum in the case of heat).

Flux examples:

• \( \rho \mathbf{v} \) : mass flux
• \( \rho u \mathbf{v} \):flux of x component of momentum
• \( \rho v \mathbf{v} \):flux of y component of momentum
• \( \rho e \mathbf{v} \):flux of internal energy
• \( \rho (e+\frac{v^2}{2}) \mathbf{v} \):flux of total energy

• diffusion flux= total flux - convective flux