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日本語

The flickering of flames is a very familiar phenomenon that is easy to observe. At the same time, it is also a mysterious and interesting phenomenon with vast complexity. For example, once the flickering flames have interfered with each other, only the stable flickering mode is selectively expressed. Depending on the distance between the flames, the "in-phase mode" that fluctuates in the same phase and the "anti-phase mode" that fluctuates in the opposite phase are selectively expressed. Also, the frequency of the fluctuation differs among these modes, which is a curious phenomenon. Although it is possible to achieve various fluctuating states in this way, there is no example that shows "stopping the flickering by interfering with the fluctuating flames." In the past, it was shown that this state can be achieved by arranging three flames (known as "death mode" in reference to the complete absence of movement). However, researchers have yet to understand the reason why death mode cannot be achieved with two flames.

When examining this theme, the research team found that the death mode is expressed by adjusting the distance between the two flames closer or further apart in a certain cycle.

"When conducting experiments involving flame-to-flame interference, flickering will temporarily stop if the flames are gradually brought closer or further apart," explains Dr. Ju Xiaoyu, lead author and researcher at the time of the project. "However, if the flames are kept in that position, they will eventually start flickering again. Since the flames eventually flicker, we know that flickering is a stable state. The fact that there is a delay period until the flames settle into a stable state means that if we can create a situation where flickering can be stopped within that time scale, the flickering should be stopped permanently. We were able to prove that this prediction is correct by periodically adjusting the distance between flames closer and further apart. We also demonstrated that the reason for this phenomenon can be explained by hydrodynamic properties. Moving forward, we will proceed with research aimed at constructing a theory."

"It has been known that the flame flickering mode is determined by interference between flames," says Professor Yuji Nakamura, leader of the research team. "Researchers in applied physics have attempted to explain this phenomenon as nonlinear physics instead of combustion engineering. Nevertheless, their explanation felt inadequate to me due to its failure to consider hydrodynamics. In response, I began to research this theme in earnest. I was amazed to witness a phenomenon in which flickering temporarily stopped in an intermediate state between in-phase and anti-phase flickering. I felt a strong desire to elucidate this mysterious transition state, a theme which has not been addressed by previous research. From the beginning, I had the idea of constantly adjusting the distance between flames to take advantage of the time delay until they settled into a stable state. Ultimately, I was able to organize this method with the help of Dr. Ju."