Taking the shock out of predicting shock wave behavior with precise computational modeling

Yokohama National University

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Engineers need to precisely predict how instant and strong pressure changes initiate and dissipate to prevent damage during rocket launches, for example. A team from YOKOHAMA National University has detailed how computational models represent a type of shock wave differently than theoretical or physical predictions do. This new understanding could help improve predictions, the researchers said.

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Credit: YOKOHAMA National University

Shock waves should not be shocking — engineers across scientific fields need to be able to precisely predict how the instant and strong pressure changes initiate and dissipate to prevent damage. Now, thanks to a team from YOKOHAMA National University, those predictions are even better understood.

In work published on Aug. 19 in the Physics of Fluids, the researchers detailed how computational models used to simulate shock wave behavior represents the “very weak shock waves” in a way that is distinctly different from both theoretical predictions and physical measurements.

Shock waves comprise the pressure that pushes out from an explosion or from an object moving faster than sound, like a supersonic jet. Weak shockwaves refer to the same changes in pressure, density and velocity, but they are much smaller than the larger waves and move closer to the speed of sound. However, current computational modeling approaches have difficulty accurately representing these very weak shock waves, according to co-author Keiichi Kitamura, professor, Faculty of Engineering, YOKOHAMA National University.

“Shock waves cause instantaneous compression, resulting in increased entropy; thus, precise computations of flows involving shock waves are crucial,” said co-author Keiichi Kitamura, professor, Faculty of Engineering, YOKOHAMA National University.

Entropy refers to disorder, which in seeming contradiction to expected physical behaviors, increases as the wave moves. That disorder is at the crux of shock wave simulations, according to Kitamura. Conventional computational approaches categorize very weak shock waves as “diffused,” but that label doesn’t account for the wave’s more nuanced variables, especially as it moves.

“Finite volume methods are commonly utilized to address the discontinuity in numerical simulations as they can conserve variables even at shock discontinuities,” Kitamura said, explaining that finite volume methods refer to the specific number of cells used in a computational representation. “However, computing shock waves using finite volume methods is not always stable and, under certain conditions, presents challenges owing to their discontinuous nature.”

In an analysis focused on understanding the specific properties of numerically represented shock waves, the researchers found that the final state of a moving shock wave can be classified into three regimes: dissipated, transitional and thinly captured. It appeared, Kitamura said, that uninterrogated numerical simulations automatically adjusted assumed physical parameters of a shock wave to make it match the calculated entropy.

“This work identified the mechanism of the diffused weak shocks — it was caused in the entropy generation process within the numerically expressed shockwaves,” Kitamura said. “Our findings will bridge the understanding gap between theoretical and physical weak shock waves, which could potentially contribute to safer, more economical and more accurate designs of future rockets and supersonic aircraft.”

Gaku Fukushima, postdoctoral researcher in the Department of Mechanical Engineering at Université de Sherbrooke in Canada, served as the corresponding author on this paper. At the time of the research, Fukushima was a Japan Society for the Promotion of Science postdoctoral fellow at YOKOHAMA National University.

The Japan Society for the Promotion of Science supported this research.

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YOKOHAMA National University (YNU) is a leading research university dedicated to academic excellence and global collaboration. Its faculties and research institutes lead efforts in pioneering new academic fields, advancing research in artificial intelligence, robotics, quantum information, semiconductor innovation, energy, biotechnology, ecosystems, and smart city development. Through interdisciplinary research and international partnerships, YNU drives innovation and contributes to global societal advancement.

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Journal

Physics of Fluids

DOI

10.1063/5.0282374 

Article Title

Peculiarity of moving weak shock computations: Entropy generation analysis of numerically expressed shock waves

Hurricane Outages: Analysis Details The Where, And Who, Of Increased Future Power Cuts

Devastation in Asheville, North Carolina, caused by Hurricane Helene. Photo Credit: Bill McMannis, Wikipedia Commons

October 18, 2025 

By Eurasia Review


Georgia and northern Florida are likely to be hardest hit by increasing hurricane-induced power outages along the Atlantic coast in the future, with Hispanic, non-white, low-income and elderly populations most affected, according to new research led by the University of Michigan.



Hurricanes are predicted to become even more frequent and severe in the coming years if the planet’s temperatures rise by another 1.5 degrees Celsius over pre-industrial levels—expected by the end of the century without drastic action taken.

The total 3 C rise will bring increased outages to areas that have historically seen few service interruptions, such as the northern Atlantic Coast. And those increases will nearly double the costs of outages, from today’s $6.2 billion per year average to $11 billion in today’s dollars.

The findings, funded in part by the U.S. Environmental Protection Agency and published in the journal PNAS, underscore the need for planning and resource allocations to prepare for what’s coming.

“There are parts of the country where we expect to see more outages, particularly northern Florida, the southern Atlantic, such as North Carolina and South Carolina, and some areas up into the mid-Atlantic,” said Seth Guikema, U-M professor of civil and environmental engineering, as well as industrial and operations engineering, and co-corresponding author of the study. “Then there are areas where we have more uncertainty, places like Texas where our models suggest they’ll have fewer outages.”

Lower-income communities already experience longer waits for service restoration in some cases, and U-M’s research shows that problem is likely to worsen.

To produce its analysis, U-M and its research partners combined data from models and data sets covering climate, hurricanes and information about the people living in affected regions:Simulated hurricanes, 28,000 of them, based on atmospheric and oceanic data, processed by co-author, Kerry Emmanuel, formerly of M.I.T. and now chief scientific officer at WindRisk Tech.

Historic outage data at the Census tract level—possibly including localized data as specific as wind characteristics, soil moisture and tree root depth.
An evaluation, based on historical hurricane tracks and projections, as well as Census data, of which groups of people would be impacted the most.
The Interruption Cost Estimate Calculator, which measures costs from outages as well as estimates the benefits of efforts to improve reliability.

“What we wind up with is the areas that are, and will be, at highest risk for power outages,” said Zaira Pagan Cajigas, a U-M Ph.D. graduate in industrial and operations engineering and co-lead author of the research paper. “We can go further and see the population makeup in those areas, and that’s how we identified that Hispanics, non-whites, low-income and elderly residents bear the brunt of these incidents.”

Roughly 78% of major power outages in the United States result from weather events, and those events are occurring more often in recent years. Tropical cyclones are responsible for nine out of 10 major outages. As Earth exceeds the Paris Agreement warming target, they are intensifying faster, bringing more rainfall, moving more slowly and penetrating further inland.

“Our hope is that this analysis will help government agencies, utilities and individual businesses and residents better understand where system hardening and other climate adaptation actions need to be taken, and the potential degree of change in outage risk and costs in the future,” Guikema said.

Hurricane outages: Analysis details the where, and who, of increased future power cuts

A new analytical tool from U-M provides guidance for municipal and emergency planning

University of Michigan

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Georgia and northern Florida are likely to be hardest hit by increasing hurricane-induced power outages along the Atlantic coast in the future, with Hispanic, non-white, low-income and elderly populations most affected, according to new research led by the University of Michigan.

 

Hurricanes are predicted to become even more frequent and severe in the coming years if the planet's temperatures rise by another 1.5 degrees Celsius over pre-industrial levels—expected by the end of the century without drastic action taken. 

 

The total 3 C rise will bring increased outages to areas that have historically seen few service interruptions, such as the northern Atlantic Coast. And those increases will nearly double the costs of outages, from today's $6.2 billion per year average to $11 billion in today's dollars.

 

The findings, funded in part by the U.S. Environmental Protection Agency and published in the journal PNAS, underscore the need for planning and resource allocations to prepare for what's coming. 

 

"There are parts of the country where we expect to see more outages, particularly northern Florida, the southern Atlantic, such as North Carolina and South Carolina, and some areas up into the mid-Atlantic," said Seth Guikema, U-M professor of civil and environmental engineering, as well as industrial and operations engineering, and co-corresponding author of the study. "Then there are areas where we have more uncertainty, places like Texas where our models suggest they'll have fewer outages."

 

Lower-income communities already experience longer waits for service restoration in some cases, and U-M's research shows that problem is likely to worsen. 

 

To produce its analysis, U-M and its research partners combined data from models and data sets covering climate, hurricanes and information about the people living in affected regions:

 

• Simulated hurricanes, 28,000 of them, based on atmospheric and oceanic data, processed by co-author, Kerry Emmanuel, formerly of M.I.T. and now chief scientific officer at WindRisk Tech.

• Historic outage data at the Census tract level—possibly including localized data as specific as wind characteristics, soil moisture and tree root depth.

• An evaluation, based on historical hurricane tracks and projections, as well as Census data, of which groups of people would be impacted the most.

• The Interruption Cost Estimate Calculator, which measures costs from outages as well as estimates the benefits of efforts to improve reliability.

 

"What we wind up with is the areas that are, and will be, at highest risk for power outages," said Zaira Pagan Cajigas, a U-M Ph.D. graduate in industrial and operations engineering and co-lead author of the research paper. "We can go further and see the population makeup in those areas, and that's how we identified that Hispanics, non-whites, low-income and elderly residents bear the brunt of these incidents."

 

Roughly 78% of major power outages in the United States result from weather events, and those events are occurring more often in recent years. Tropical cyclones are responsible for nine out of 10 major outages. As Earth exceeds the Paris Agreement warming target, they are intensifying faster, bringing more rainfall, moving more slowly and penetrating further inland.

 

"Our hope is that this analysis will help government agencies, utilities and individual businesses and residents better understand where system hardening and other climate adaptation actions need to be taken, and the potential degree of change in outage risk and costs in the future," Guikema said.
 

The research team also includes Charles Fant, Brent Boehlert and C.X. Maier of Industrial Economics Inc., and Corrinne Hartin and Marcus Sarofim of the EPA.

 

Study: Climate Change Impacts on Tropical Cyclone-Induced Power Outage Risk: Socio-Demographic Differences in Outage Burdens (DOI: 10.1073/pnas.2502266122)

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Journal

Proceedings of the National Academy of Sciences

DOI

10.1073/pnas.2502266122 

 

US Cannabis laws and opioid use among commercially insured patients with cancer diagnoses

JAMA Health Forum

About The Study:

 This study’s findings indicate cannabis may be a substitute for opioids in the management of cancer-related pain. However, further research directly observing cannabis use is needed to evaluate the efficacy of cannabis as a treatment for cancer-related pain.

Corresponding Author: To contact the corresponding author, Victoria Bethel, MSN, email vbethel@uga.edu.

To access the embargoed study: Visit our For The Media website at this link https://media.jamanetwork.com/

(doi:10.1001/jamahealthforum.2025.3512)

Editor’s Note: Please see the article for additional information, including other authors, author contributions and affiliations, conflict of interest and financial disclosures, and funding and support.

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About JAMA Health Forum: JAMA Health Forum is an international, peer-reviewed, online, open access journal that addresses health policy and strategies affecting medicine, health and health care. The journal publishes original research, evidence-based reports and opinion about national and global health policy; innovative approaches to health care delivery; and health care economics, access, quality, safety, equity and reform. Its distribution will be solely digital and all content will be freely available for anyone to read.

 

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Journal

JAMA Health Forum

 

Chemicals might be hitching a ride on nanoplastics to enter your skin

Researchers discover that environmental coatings on microscopic plastic particles help them evade immune responses in skin cells.

Texas A&M University

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Dr. Wei Xu and his research team at Texas A&M University are uncovering how ocean-exposed nanoplastics interact with skin cells, highlighting new concerns about microscopic pollution and human health.

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Credit: Texas A&M University

Plastic is ubiquitous in the modern world, and it’s notorious for taking a long time to completely break down in the environment — if it ever does.

But even without breaking down completely, plastic can shed tiny particles — called nanoplastics because of their extremely small size — that scientists are just now starting to consider in long-term health studies.

One of those scientists is Dr. Wei Xu, an associate professor in the Texas A&M College of Veterinary Medicine and Biomedical Sciences’ Department of Veterinary Physiology & Pharmacology. Xu’s current work is focused on what happens when nanoplastics interact with seawater, where they can pick up some curious hitchhikers in the form of chemicals and organic components.

“When particles are released into the environment, they can interact with a lot of different materials that modify their surfaces, possibly including proteins, chemicals, and toxins,” Xu said. “Most people are concerned with what happens when you accidentally ingest nanoplastics, but our work looks at how they might be getting into the body through the skin and what they might be bringing with them.”

As they demonstrated in a recent publication, Xu and his team have discovered that nanoplastics with environmental coatings can sneak past some of the skin’s defenses at the microscopic level.

“We found that particles with the environmental coating accumulated in certain areas inside the cell and seemed successful at avoiding its ‘garbage disposal’ system, which might try to kill or expel them,” Xu said. “It’s like they’re wearing camouflage that allows them to stay inside the cell longer.”

While the long-term health consequences of nanoplastics in the body are still being studied, Xu’s research highlights the importance of the skin as a target for nanoplastics and the ability of the environment to alter particles before they’re absorbed by the body.

“While the nanoplastics themselves are a health concern, we also want to better understand these environmental coatings and what those may do once inside the body,” Xu said.

Tiny beads, big discoveries

To understand how nanoplastics affected by the environment enter the skin, Xu and his team created their own nanoplastic beads augmented by ocean water.

“There are vendors that produce nanoplastic particles for scientific research, but these particles have never been out in the environment,” Xu said. “So, before we conducted the toxicity assessment, we used water collected from the ocean off the coast of Corpus Christi.”

After letting the particles interact with the seawater for one to two weeks, Xu and his team were able to analyze the particles’ environmental coatings to see what kind of changes occurred. Then, they tested how the particles make their way inside cultured skin cells.

“We had conducted previous research using plain nanoplastic beads that showed how they induce a reaction from skin cells,” Xu said. “It was significant seeing how the beads with environmental coatings were better able to avoid the attack by the immune system.”

Tackling a complex problem

Xu’s research on the skin and environmental effects of particles is helping scientists understand that some of the trickiest problems in toxicology are even more complex than they had previously realized.

“In our research, we had to focus on a specific type of environmental coating, so we looked at proteins,” Xu said. “But what about those from algal blooms or other toxins? What happens when there are floods and water mixes with other contaminants? We haven’t had the chance to explore how these things intersect yet.”

Even if researchers do find solutions to preventing absorption of nanoplastics with certain kinds of environmental coatings, there’s no guarantee that those will continue to work.

“What if the environment is totally changed in 10 or 20 years and there are different coatings on the particles? We may have to keep coming up with new strategies to control them,” Xu said.

The first step, according to Xu, is for there to be better standardization for research on nanoplastic particles, which he hopes his research will help drive forward.

“I’ve had students look at publications on the same particle and find different results because other researchers aren’t required to consider environmental coatings,” he said. “We need better consistency for the long term.”

Another step is to fully analyze all the coating types that Xu and his team found in their study of seawater.

“We’ve already had people ask us about other types of coatings besides proteins,” he said. “It will be a lot of work, but it’s critical if we’re to understand the full scope of the problem.”

By Courtney Price, Texas A&M University College of Veterinary Medicine and Biomedical Sciences

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Journal

Journal of Hazardous Materials

DOI

10.1016/j.jhazmat.2025.138722 

Method of Research

Experimental study

Subject of Research

Cells

Article Title

Environmental protein corona on nanoplastics altered the responses of skin keratinocytes and fibroblast cells to the particles

Article Publication Date

15-Aug-2025

COI Statement

The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Leisha Martin declares corporate affiliation with MNT SmartSolutions, Inc. and LEI NanoTech.