“…Later, they [4] observed flow pattern and temperature distribution in rotating drums subject to a sudden acceleration and inner surface heating, using the laser light-sheet method and ironconstantan thermocouples, respectively. In order to evaluate quantitatively the temperature distribution in the rotating drums, Kawashima and Yang [5] employed temperaturesensitive liquid crystals as a noninvasive method. A series of studies was focused on visualization of two-dimensional This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.…”