In order to shed light on the initial mechanism of dust entrainment behind a moving shock wave, the particles' motion behind a planar shock wave was investigated using horizontally placed shock tubes and a direct photographic technique synchronized with the shock wave motion. The drag coefficient measurement of an accelerating spherical particle (0.3–5.57 mm in diameter) was performed. The obtained drag coefficients were found to be higher than those from the standard drag curve. On average, the difference was about 20% for a relative Reynolds number from 103 and 105. The initial motion of a particle just lifted-up from the wall was also examined using the other shock tube. The results indicated that the velocity and speed of rotation of particles were strongly affected by the floor conditions. It was also found that the particle's initial rotation does not play a major role in the particle rise.

Microwave heating of a dielectric in a cavity was analyzed numerically with the FDTD method with the aim of devising new methods for reducing uneven heating typical of microwaving. The dielectric was assumed to be water and the frequency of a microwave was taken to be 1 GHz. It was found that the electric field is highly dependent on the position of the dielectric in a cavity. The temperature distribution reflects the profile of the RMS value of the electric field in the dielectric, although there appears to be no effect of the short wavelength typical of the electric field. The heating rate depends on the position of the dielectric. In the case of a higher effective loss factor a microwave decays immediately after entering the dielectric, and the temperature of the interior remains low. These results indicate that the uneven heating is due to at least two causes: standing wave and rapid decay of a microwave.

No abstract

No abstract

No abstract