# Thermal Diffusivity

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Related to Thermal Diffusivity: Fourier number

## thermal diffusivity

[′thər·məl ‚di·fyü′siv·əd·ē]
(physics)
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

## Thermal Diffusivity

a physical parameter of a substance that characterizes the rate of change of its temperature in transient thermal processes. Thermal diffusivity is a measure of the thermal-inertia properties of a substance. It is numerically equal to the ratio of the substance’s thermal conductivity and the product of its specific heat (at constant pressure) and density. Thermal diffusivity is expressed in m2/sec.

## thermal diffusivity

The thermal conductivity divided by the product of the specific heat and unit weight; an index of the ease with which a material undergoes a change in temperature.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.
References in periodicals archive ?
where u = t - [tau], [gamma] = [r.sup.2.sub.0]/([r.sup.2.sub.0] + 4[alpha]u), [alpha] is the thermal diffusivity, [rho] is the density, and cp is the specific heat.
Our results as presented in Figure 7 show that the bark-based insulation boards produced do not have a very low thermal conductivity but do have comparatively low thermal diffusivity values and could therefore be well suited for heat storage-optimized insulation materials for buildings.
As can be seen from Figures 10 and 11, this effect decreases when the ratio between the thermal diffusivity of the grout and that of the ground increases; this ratio is 0.27 for BG and 0.93 for TEG.
While concrete may have a cold "feel" as do other masonry floors due to its thermal diffusivity, it is not cold.
SigmaSoft, for instance, accepts thermal conductivity data and, in conjunction with specific heat capacity and density, calculates thermal diffusivity.
To characterize the rapidity of heat propagation through the composite, the thermal diffusivity coefficient of the composite was measured using a LFA 457 laser flash apparatus.
The Rayleigh number (Ra) is defined as the product of the Grashof number (Gr), which describes the relationship between buoyancy and viscosity within a fluid, and the Prandtl number (Pr), which describes the relationship between momentum diffusivity and thermal diffusivity. For free convection near a vertical wall, this number is defined as follows:
In a laser flash thermal diffusivity test, a small specimen is subjected to a quick, intense radiant laser pulse after thermal equilibration at the test temperature of interest.
where [G.sub.Fo] is the analytical solution, also known as the G-factor, [F.sub.o] is the Fourier number defined as [F.sub.o]=4[alpha]t/[d.sup.2], a is the ground thermal diffusivity, d is the borehole diameter, and k is the ground thermal conductivity.
Thermal diffusivity is defined as the thermal conductivity divided by the specific heat and density.
Diamond-like carbon (DLC) possesses high thermal conductivity, thermal diffusivity, and thermal radiation; furthermore, the coefficient of thermal expansion (CTE) of DLC is similar to that of GaN.

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