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Convection is often categorised or described by the main effect causing the convective flow; for example, thermal convection. Convection cannot take place in most solids because neither bulk current flows nor significant diffusion of matter can take place. Granular convection is a similar phenomenon in granular material instead of fluids.
Convection (or convective heat transfer) is the transfer of heat from one place to another due to the movement of fluid. Although often discussed as a distinct method ...
Another form of convection is forced convection. In this case, the fluid is forced to flow by using a pump, fan, or other mechanical means. Convective heat transfer , or simply, convection, is the transfer of heat from one place to another by the movement of fluids , a process that is essentially the transfer of heat via mass transfer .
Maxwell writes that convection as such "is not a purely thermal phenomenon". [55] In thermodynamics, convection in general is regarded as transport of internal energy. If, however, the convection is enclosed and circulatory, then it may be regarded as an intermediary that transfers energy as heat between source and destination bodies, because ...
In thermodynamics, the heat transfer coefficient or film coefficient, or film effectiveness, is the proportionality constant between the heat flux and the thermodynamic driving force for the flow of heat (i.e., the temperature difference, ΔT).
The Nusselt number is the ratio of total heat transfer (convection + conduction) to conductive heat transfer across a boundary. The convection and conduction heat flows are parallel to each other and to the surface normal of the boundary surface, and are all perpendicular to the mean fluid flow in the simple case.
Heat flux vector q is composed of three macroscopic fundamental modes, which are conduction (q k = −k∇T, k: thermal conductivity), convection (q u = ρc p uT, u: velocity), and radiation (=, (), ω: angular frequency, θ: polar angle, I ph,ω: spectral, directional radiation intensity, s: unit vector), i.e., q = q k + q u + q r.
Traditionally, thermodynamics has recognized three fundamental laws, simply named by an ordinal identification, the first law, the second law, and the third law. [ 1 ] [ 2 ] [ 3 ] A more fundamental statement was later labelled as the zeroth law after the first three laws had been established.