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For heat flow, the heat equation follows from the physical laws of conduction of heat and conservation of energy (Cannon 1984). By Fourier's law for an isotropic medium, the rate of flow of heat energy per unit area through a surface is proportional to the negative temperature gradient across it:
Thermal conduction is the diffusion of thermal energy (heat) within one material or between materials in contact. The higher temperature object has molecules with more kinetic energy; collisions between molecules distributes this kinetic energy until an object has the same kinetic energy throughout.
We obtain the distribution of the property i.e. a given two dimensional situation by writing discretized equations of the form of equation (3) at each grid node of the subdivided domain. At the boundaries where the temperature or fluxes are known the discretized equation are modified to incorporate the boundary conditions.
[2] [3] It is also used to numerically solve parabolic and elliptic partial differential equations, and is a classic method used for modeling heat conduction and solving the diffusion equation in two or more dimensions. [4] It is an example of an operator splitting method. [5]
Thermal conduction rate, thermal current, thermal/heat flux, thermal power transfer P = / W ML 2 T −3: Thermal intensity I = / W⋅m −2: MT −3: Thermal/heat flux density (vector analogue of thermal intensity above) q
As an example, number X11 denotes the Green's function that satisfies the heat equation in the domain (0 < x < L) for boundary conditions of type 1 at both boundaries x = 0 and x = L. Here X denotes the Cartesian coordinate and 11 denotes the type 1 boundary condition at both sides of the body.
In the case of a moving heat source applied to a plate that is so thin that temperature does not vary in the through-thickness dimension, the third term becomes zero, and the problem is two-dimensional conduction. [2] [3] The factors that determine whether temperature varies through the thickness include:
Conduction heat flux q k for ideal gas is derived with the gas kinetic theory or the Boltzmann transport equations, and the thermal conductivity is =, -, where u f 2 1/2 is the RMS (root mean square) thermal velocity (3k B T/m from the MB distribution function, m: atomic mass) and τ f-f is the relaxation time (or intercollision time period ...