Based on their findings, the authors recommend slowly pouring hot water into the coffee grounds to increase the amount of time they have soaked the beans in the water. However, when you pour water slowly, the resulting jet sticks to the gush (“teapot effect”) and there is not enough mixing of the site. Instead, it simply settles down to the bottom and reduces the extraction yield. “If you have a thin jet, it tends to break up into droplets.” Co-author Margot Young said. “That’s something you want to avoid with these pouring outfits, because it means that the jets can’t effectively mix the coffee upholstery.”
Small jet diameter and impact on dynamics.
Credit: E. Park et al. , 2025
It’s where you increase the height you pour. This, according to the author, gives more energy from gravity and increases the granular coffee-covered mix. But again, there’s something like pouring from too much height, causing the water jet to fall apart. The ideal height is less than 50 cm (approximately 20 inches) above the filter. The classic goosenecked tea kettle has proven ideal for achieving its optimum height. Future research may explore the effects of changing the grain size of coffee grounds.
Increased extraction yields and, moreover, it is becoming increasingly difficult to grow the most common coffee seeds due to continuous climate change, which reduces the amount of coffee grounds that use the substance. “Coffee is becoming more difficult to grow, so coffee prices are likely to increase over the next few years,” co-author Arnold Matighen I told a new scientist. “The idea for this study was to actually see if we could do anything by reducing the amount of coffee beans needed while maintaining the same amount of brewing.
However, potential applications are not limited to brewed coffee. The authors note that this same liquid jet/submerged granular bed interaction is also involved in soil erosion and wastewater treatment, for example, from waterfalls. Wastewater treatment is used to promote wastewater and enhance biodegradation of organic matter. “Dams operate on a much larger scale, but they can suffer similar dynamics, and finding ways to reduce the jet height of the dam can reduce erosion and increase the health of the dam,” they write.
Liquid Physics, 2025. doi: 10.1063/5.0257924 (About DOI).
