Search results
Results from the WOW.Com Content Network
Energy flux is the rate of transfer of energy through a surface. The quantity is defined in two different ways, depending on the context: Total rate of energy transfer (not per unit area); [1] SI units: W = J⋅s −1. Specific rate of energy transfer (total normalized per unit area); [2] SI units: W⋅m −2 = J⋅m −2 ⋅s −1:
Energy flux, the rate of transfer of energy through a unit area (J·m −2 ·s −1). The radiative flux and heat flux are specific cases of energy flux. Particle flux, the rate of transfer of particles through a unit area ([number of particles] m −2 ·s −1) These fluxes are vectors at each point in space, and have a definite magnitude and ...
In physics, the Poynting vector (or Umov–Poynting vector) represents the directional energy flux (the energy transfer per unit area, per unit time) or power flow of an electromagnetic field. The SI unit of the Poynting vector is the watt per square metre (W/m 2 ); kg/s 3 in base SI units.
Fick's first law relates the diffusive flux to the gradient of the concentration. It postulates that the flux goes from regions of high concentration to regions of low concentration, with a magnitude that is proportional to the concentration gradient (spatial derivative), or in simplistic terms the concept that a solute will move from a region of high concentration to a region of low ...
Flux F through a surface, dS is the differential vector area element, n is the unit normal to the surface. Left: No flux passes in the surface, the maximum amount flows normal to the surface. Right: The reduction in flux passing through a surface can be visualized by reduction in F or dS equivalently (resolved into components, θ is angle to ...
Mathematically, mass flux is defined as the limit =, where = = is the mass current (flow of mass m per unit time t) and A is the area through which the mass flows.. For mass flux as a vector j m, the surface integral of it over a surface S, followed by an integral over the time duration t 1 to t 2, gives the total amount of mass flowing through the surface in that time (t 2 − t 1): = ^.
Prominent examples include Fourier's law of heat conduction and the Navier–Stokes equations, which describe, respectively, the response of heat flux to temperature gradients and the relationship between fluid flux and the forces applied to the fluid. These equations also demonstrate the deep connection between transport phenomena and ...
The rate of diffusion N A is usually expressed as the number of moles diffusing across unit area in unit time. As with the basic equation of heat transfer, this indicates that the rate of force is directly proportional to the driving force, which is the concentration gradient. This basic equation applies to a number of situations.