Flux density

Stream Density is a general basic physical term that is used in the following areas:

• in the case of transport phenomena ( heat transfer , mass transfer, and hydroaerodynamics ), the flux density of a scalar quantity is understood to mean the quantity of this quantity that passes through a unit area per unit time. Usually flux density${\displaystyle \mathrm{<span\; class="mwe-math-element"><span\; class="mwe-math-mathml-inline\; mwe-math-mathml-a11y"\; style="display:\; none;">f</span></span>}}$ {\ displaystyle f} determined by the formula${\displaystyle \mathrm{<span\; class="mwe-math-element"><span\; class="mwe-math-mathml-inline\; mwe-math-mathml-a11y"\; style="display:\; none;">f</span></span>}\stackrel{<span\; class="mwe-math-element"><span\; class="mwe-math-mathml-inline\; mwe-math-mathml-a11y"\; style="display:\; none;">\to </span></span>}{\mathrm{<span\; class="mwe-math-element"><span\; class="mwe-math-mathml-inline\; mwe-math-mathml-a11y"\; style="display:\; none;">v</span></span>}}}$ {\ displaystyle f {\ vec {v}}} / V, where V is the volume over which f is distributed.
• in electrodynamics , flux is usually defined as the integral of a vector quantity over a finite surface.