Face Mask Construction, Materials Matter for Containing Coughing, Sneezing Droplets

While the use of face masks in public has been widely recommended by health officials during the current COVID-19 pandemic, there are relatively few specific guidelines pertaining to mask materials and designs. A study in Physics of Fluids looks to better understand which types are best for controlling respiratory droplets that could contain viruses. The team experimented with different choices in material and design to determine how well face masks block droplets as they exit the mouth.

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Respiratory Droplet Motion, Evaporation and Spread of COVID-19-Type Pandemics

It is well established the COVID-19 virus is transmitted via respiratory droplets. Consequently, much research targets better understanding droplet motion and evaporation. In Physics of Fluids, researchers developed a mathematical model for the early phases of a COVID-19-like pandemic using the aerodynamics and evaporation characteristics of respiratory droplets. The researchers modeled the pandemic dynamics with a reaction mechanism and then compared the droplet cloud ejected by an infected person versus one by a healthy person.

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Flushing Toilets Create Clouds of Virus-Containing Particles

Researchers used a computer simulation to show how a flushing toilet can create a cloud of virus-containing aerosol droplets that is large and widespread and lasts long enough that the droplets could be breathed in by others. With recent studies showing the COVID-19 virus can survive in the human digestive tract and show up in feces of the infected, this raises the possibility the disease could be transmitted with the use of toilets.

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Survival of Coronavirus in Different Cities, on Different Surfaces

One of the many questions researchers have about the COVID-19 virus is how long it remains alive after someone infected coughs or sneezes. In Physics of Fluids, researchers examine the drying time of respiratory droplets from COVID-19-infected subjects on various surfaces in six cities around the world. Using a model well established in the field of interface science, the drying time calculations showed ambient temperature, type of surface and relative humidity play critical roles.

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Bubble Dynamics Reveal How to Empty Bottles Faster

Researchers from the Indian Institute of Technology Roorkee have discovered how to make bottles empty faster, which has wide-ranging implications for many areas beyond the beverage industry. In this week’s Physics of Fluids, they explore this bottle-emptying phenomenon from the perspective of bubble dynamics on a commercial bottle by using high-speed photography. Image analysis allowed them to conceptualize various parameters, such as liquid film thickness, bubble aspect ratio, rise velocity and bottle emptying modes.

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Adjusting Processing Temperature Results in Better Hydrogels for Biomedical Applications

Biohydrogels have been studied closely for their potential use in biomedical applications, but they often move between sols and gels, depending on their temperature, changes that can pose issues depending on the intended use. In Physics of Fluids, researchers discuss their work studying the effect of temperature on hydrogels. They found that creating hydrogels at room temperature or below results in more robust materials that function more effectively when used in the body.

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Unstable Rock Pillars Near Reservoirs Can Produce Dangerous Water Waves

In many coastal zones and gorges, unstable cliffs often fail when the foundation rock beneath them is crushed. Large water waves can be created, threatening human safety. In this week’s Physics of Fluids, scientists reveal the mechanism by which these cliffs collapse, and how large, tsunami-like waves are created. Few experimental studies of this phenomenon have been carried out, so this work represents valuable new data that can be used to protect from impending disaster.

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Simulations Show Effects of Buoyancy on Drift in Florida Current

Acquiring a better understanding for how objects drift in the ocean has importance for many uses, but most models lack a systematic approach. One new effort looks to provide a clearer alternative. Researchers have released the results from an experiment aimed at tracking different objects as they drift in the Florida Current. Using satellite data, the group developed a new model for how objects drift. They discuss their work in this week’s Physics of Fluids.

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Spider-Man-Style Robotic Graspers Defy Gravity

Traditional methods of vacuum suction and previous vacuum suction devices cannot maintain suction on rough surfaces due to vacuum leakage, which leads to suction failure. Researchers Xin Li and Kaige Shi developed a zero-pressure difference method to enhance the development of vacuum suction units. Their method overcame leakage limitations by using a high-speed rotating water ring between the surface and suction cup to maintain the vacuum. They discuss their work in Physics of Fluids.

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Analysis of Galileo’s Jupiter Entry Probe Reveals Gaps in Heat Shield Modeling

The entry probe of the Galileo mission to Jupiter entered the planet’s atmosphere in 1995 in fiery fashion, generating enough heat to cause plasma reactions on its surface. The data relayed about the burning of its heat shield differed from the effects predicted in fluid dynamics models, and new work examines what might have caused such a discrepancy.

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Stabilizing Multilayer Flows May Improve Transportation of Heavy Oils

During the past 20 years, the oil industry has begun to transition away from light oils toward heavier oils. But transporting heavy oils cost-effectively is a challenge because heavy oils are viscous — essentially a thick, sticky and semifluid mess. One way to outmaneuver this problem, reported in Physics of Fluids, is a viscoplastic lubrication technique.

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