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Since the early 1960s, the laser flash method of thermal diffusivity measurement has been used on a large variety of materials. Several parameter estimation methods have also been used in analyzing such experiments, employing various levels of sophistication. Estimation of thermal parameters, using the models developed as part of this research, is performed on experimental data from the Oak Ridge National Laboratory in Oak Ridge, TN. The material used is carbon bonded carbon fiber (CBCF) which is designed as an insulating material for atmosphere re-entry applications. Ambient temperatures in the experiments range from 800°C to 1200°C. The approximate thermal diffusivity of the material is 0.3 mm2/sec. This research investigates the penetration of the laser flash beyond the surface of the material being heated. Three heat transfer models are presented, each with different assumptions about the initial temperature distribution inside the material. An evaluation is made of the response of the methods to factors which may enter into the experimental process. This is done in quantitative terms so as to assess the adequacy of the models in comparison to one another.

This article describes the developmen t of accurate solutions for transient three-dimensional conductive heat transfer in Cartesian coordinates for a parallelepiped which is homogeneous and has constant thermal properties. The intended use of these solutions is for verification of numerical computer programs which are used for solving transient heat conduction problems. Verification is a process to ensure that a computer code is free of errors and accurately solves the mathematical equations. The exact solutions presented in this article can have any combination of boundary conditions of specified temperature, prescribed heat flux, or imposed convection coefficient and ambient temperature on the surfaces of the parallelepiped . Additionally, spatially uniform nonzero initial condition and internal energy generation are treated. The methodology to obtain the analytical solutions and sample calculations are presented.

It has previously been shown that when a liquid drop of high viscosity is placed on a non-wettable inclined surface, it rolls down at a constant descent velocity determined by the balance between viscous dissipation and the reduction rate of its gravitational potential energy. Since increasing the roughness of the surface boosts its non-wetting property, the drop should move faster on a surface structured with macrotextures (ribbed surface). Such a surface was obtained from a superhydrophobic soot coating on a solid specimen printed with an extruder-type 3D printer. The sample became superoleophobic after a functionalization process. The descent velocity of glycerol drops of different radii was then measured on the prepared surface for varied tilting angles. Our data show that the drops roll down on the ribbed surface approximately 27% faster (along the ridges) than on the macroscopically smooth counterpart. This faster velocity demonstrates that ribbed surfaces can be promising candidates for drag-reduction and self-cleaning applications. Moreover, we came up with a modified scaling model to predict the descent velocity of viscous rolling drops more accurately than what has previously been reported in the literature.