Nav: Home

MSU-based specialists in mechanics investigated the behavior of vacuum oil in space

May 04, 2018

A research team from the Research Institute of Mechanics, MSU together with a colleague from the Center of New Space Technologies, MAI described the behavior of a liquid sheet propagating in open space. The results of the study were published in the Physics of Fluids journal.

Under standard conditions, the stability of liquid sheets generally depends on their interaction with the air. The predominant effect (the so-called Kelvin-Helmholtz instability) is manifested due to the liquid-air friction. The difference in the velocities of the gas and the liquid results in the onset of ripples, waves, and the formation of droplets near the liquid surface. Wind-generated waves on the surfaces of water are probably one of the best-known examples of this instability. The authors of the article studied theoretically the behavior of a liquid sheet in vacuum, when no interaction with the environment occurs. In the study, the authors considered the so-called vacuum oil, i.e. a liquid whose viscosity, thermal conductivity, and surface tension coefficients vary substantially with temperature (such liquids are used, among others, in oil-vapor pumps).

Studying the liquid-sheet behavior in open space is relevant to the development of new spacecraft cooling technologies. In the future, the so-called droplet cooling radiators may be used to control the thermal regime of long-mission spacecrafts. In these devices the liquid of the cooling system is fragmented by special atomizers and turns into a layer of liquid droplets moving in the open space. Since the layer of droplets has a large radiating surface, the heat is more efficiently released and the liquid is cooled more intensively. At the same time, a serious problem arises, as these drops have to be collected, liquefied, and returned back onboard the spacecraft. One of possible solutions of this problem is to collect the cooled drops onto a specially organized liquid sheet. The main issue of the paper is to study the hydrodynamic stability of such a sheet in the open space conditions.

"Liquid films and sheets tend to be broken into droplets due to the Kelvin-Helmholtz instability, associated with friction between air and liquid. However, this disability is eliminated in open space; accordingly, we need to study other possible mechanisms of instability and reasons for liquid fragmentation. We found out what other types of instabilities may occur in liquid sheets when they propagate in vacuum, but their flow is considerably non-isothermal due to heat radiation from the sheet surface," - explained Professor Alexander Osiptsov, a co-author of the work and the Head of Laboratory for Mechanics of Multiphase Media, Research Institute of Mechanics, MSU.

Using the classical approaches of hydrodynamic-stability theory, the researchers gave a mathematical explanation of the behavior exhibited by a vacuum-oil sheet in the open space. It turned out that in the absence of the main (Kelvin-Helmholtz) instability mechanism other instabilities may develop, namely those associated with viscosity and surface tension gradients. Due to the heat radiation from the sheet surface, temperature differences arise both along the surface of the sheet and inside it. In turn, these temperature gradients cause nonuniformities in the viscosity and surface tension and the onset of new instability mechanisms.

The scientists described the occurrence of instabilities in a flow of liquid from the mathematical point of view, studied the development of short- and long-wave disturbances with time, and determined the most 'dangerous' of them. In their further work, the scientists plan to continue the development of the theoretical model and to describe more complicated processes that may occur in the system.

"By now we've studied only the initial stage, i.e. the behavior of small disturbances. We've determined the conditions when the disturbances are damped or grow and established the instability criteria. In the future, we'll have to deal with more complicated problems: to study the development of disturbances in the non-linear stage, to estimate the time intervals over which areas of nonuniform thickness of the sheet or even holes in it are formed, and to find the rate of sheet's fragmentation into droplets. And that is most important, we have to learn how to control the process and stabilize the sheet flow regime in open space," - added A. Osiptsov.
-end-


Lomonosov Moscow State University

Related Behavior Articles:

Religious devotion as predictor of behavior
'Religious Devotion and Extrinsic Religiosity Affect In-group Altruism and Out-group Hostility Oppositely in Rural Jamaica,' suggests that a sincere belief in God -- religious devotion -- is unrelated to feelings of prejudice.
Brain stimulation influences honest behavior
Researchers at the University of Zurich have identified the brain mechanism that governs decisions between honesty and self-interest.
Brain pattern flexibility and behavior
The scientists analyzed an extensive data set of brain region connectivity from the NIH-funded Human Connectome Project (HCP) which is mapping neural connections in the brain and makes its data publicly available.
Butterflies: Agonistic display or courtship behavior?
A study shows that contests of butterflies occur only as erroneous courtships between sexually active males that are unable to distinguish the sex of the other butterflies.
Sedentary behavior associated with diabetic retinopathy
In a study published online by JAMA Ophthalmology, Paul D.
Curiosity has the power to change behavior for the better
Curiosity could be an effective tool to entice people into making smarter and sometimes healthier decisions, according to research presented at the annual convention of the American Psychological Association.
Campgrounds alter jay behavior
Anyone who's gone camping has seen birds foraging for picnic crumbs, and according to new research in The Condor: Ornithological Applications, the availability of food in campgrounds significantly alters jays' behavior and may even change how they interact with other bird species.
A new tool for forecasting the behavior of the microbiome
A team of investigators from Brigham and Women's Hospital and the University of Massachusetts have developed a suite of computer algorithms that can accurately predict the behavior of the microbiome -- the vast collection of microbes living on and inside the human body.
Is risk-taking behavior contagious?
Why do we sometimes decide to take risks and other times choose to play it safe?
Neural connectivity dictates altruistic behavior
A new study suggests that the specific alignment of neural networks in the brain dictates whether a person's altruism was motivated by selfish or altruistic behavior.

Related Behavior Reading:

Behave: The Biology of Humans at Our Best and Worst
by Robert M. Sapolsky (Author)

The New York Times bestseller

“It’s no exaggeration to say that Behave is one of the best nonfiction books I’ve ever read.” —David P. Barash, The Wall Street Journal

"It has my vote for science book of the year.” Parul Sehgal, The New York Times

"Hands-down one of the best books I’ve read in years. I loved it." —Dina Temple-Raston, The Washington Post

Named a Best Book of the Year by The Washington Post and The Wall... View Details


Behavior: The Forgotten Curriculum - An RTI Approach for Nurturing Essential Life Skills (Transform Your Differentiated Instruction, Assessment, and Behavior-Management Strategies)
by Chris Weber (Author)

To fully prepare students for college, careers, and life, it is essential for educators to nurture students' behavioral skills along with their academic skills. With Behavior: The Forgotten Curriculum, you will learn how to employ the most effective behavioral and social skills activities for your particular class and form unique relationships with each and every learner. Through this personalized classroom behavior-management approach, you can anticipate potential problem areas and confidently respond to students in need of intensive and differentiated supports.

Use... View Details


Ethics for Behavior Analysts, 3rd Edition
by Jon Bailey (Author), Mary Burch (Author)

This fully-updated third edition of Jon Bailey and Mary Burch’s bestselling Ethics for Behavior Analysts is an invaluable guide to understanding and implementing the newly-revised Behavior Analyst Certification Board (BACB) Professional and Ethical Compliance Code. Featured in this new edition are case studies drawn from the author’s real-world practice with hints to guide readers toward the ethical ‘solution’ and revised chapters, including how this new edition evolved alongside the revised Code and tips for succeeding in your first job as a certified behavior analyst. The... View Details


The Survival Guide for Kids with Behavior Challenges: How to Make Good Choices and Stay Out of Trouble
by Thomas McIntyre Ph.D. (Author)

Many kids and teens have challenges when it comes to behavior. In this revised edition of his time-tested book, Thomas McIntyre provides up-to-date information, practical strategies, and sound advice to help kids learn to make smarter choices, make and keep friends, get along with teachers, take responsibility for their actions, work toward positive change, and enjoy the results of their better behavior. New to this edition are an “Are you ready to change?” quiz, updated glossary and resources, and a fresh organization and design. This is a book for any young person who needs help with... View Details


The Behavior Code: A Practical Guide to Understanding and Teaching the Most Challenging Students
by Jessica Minahan (Author), Nancy Rappaport MD (Author)

Based on a collaboration dating back nearly a decade, the authors—a behavioral analyst and a child psychiatrist—reveal their systematic approach for deciphering causes and patterns of difficult behaviors and how to match them with proven strategies for getting students back on track to learn.

The Behavior Code includes user-friendly worksheets and other helpful resources. View Details


Cognitive Behavior Therapy, Second Edition: Basics and Beyond
by Judith S. Beck (Author), Aaron T. Beck (Foreword)

The leading text for students and practicing therapists who want to learn the fundamentals of cognitive behavior therapy (CBT), this book is eminently practical and authoritative. In a highly accessible, step-by-step style, master clinician Judith S. Beck demonstrates how to engage patients, develop a sound case conceptualization, plan treatment, and structure sessions effectively. Core cognitive, behavioral, and experiential techniques are explicated and strategies are presented for troubleshooting difficulties and preventing relapse. An extended case example and many vignettes and... View Details


Subliminal: How Your Unconscious Mind Rules Your Behavior
by Leonard Mlodinow (Author)

From the bestselling author of The Drunkard’s Walk and coauthor of The Grand Design (with Stephen Hawking), a startling and eye-opening examination of how the unconscious mind shapes our experience of the world.
 
Winner of the 2013 PEN/E.O. Wilson Literary Science Writing Award
 
Over the past two decades of neurological research, it has become increasingly clear that the way we experience the world--our perception, behavior, memory, and social judgment--is largely driven by the mind's subliminal processes and not by the conscious ones, as we... View Details


How to Reach and Teach Children with Challenging Behavior (K-8): Practical, Ready-to-Use Interventions That Work
by Kaye Otten (Author), Jodie Tuttle (Author)

Interventions for students who exhibit challenging behavior

Written by behavior specialists Kaye Otten and Jodie Tuttle--who together have 40 years of experience working with students with challenging behavior in classroom settings--this book offers educators a practical approach to managing problem behavior in schools. It is filled with down-to-earth advice, ready-to-use forms, troubleshooting tips, recommended resources, and teacher-tested strategies. Using this book, teachers are better able to intervene proactively, efficiently, and effectively with students exhibiting behavior... View Details


The Dialectical Behavior Therapy Skills Workbook: Practical DBT Exercises for Learning Mindfulness, Interpersonal Effectiveness, Emotion Regulation & Tolerance (New Harbinger Self-Help Workbook)
by Matthew McKay (Author), Jeffrey C. Wood (Author), Jeffrey Brantley (Author)

A Clear and Effective Approach to Learning DBT Skills

First developed for treating borderline personality disorder, dialectical behavior therapy (DBT) has proven effective as treatment for a range of other mental health problems, especially for those characterized by overwhelming emotions. Research shows that DBT can improve your ability to handle distress without losing control and acting destructively. In order to make use of these techniques, you need to build skills in four key areas-distress tolerance, mindfulness, emotion regulation, and interpersonal... View Details


The Behavior Code Companion: Strategies, Tools, and Interventions for Supporting Students with Anxiety-Related or Oppositional Behaviors
by Jessica Minahan (Author)

Since its publication in 2012, The Behavior Code: A Practical Guide to Understanding and Teaching the Most Challenging Students has helped countless classroom teachers, special educators, and others implement an effective, new approach to teaching focused on skill-building, practical interventions, and purposeful, positive interactions with students who have mental health disorders.

Based on the success of the previous book, author Jessica Minahan has written this companion guide for educators seeking additional guidance for creating and implementing successful behavior... View Details

Best Science Podcasts 2018

We have hand picked the best science podcasts for 2018. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Inspire To Action
What motivates us to take up a cause, follow a leader, or create change? This hour, TED speakers explore stories of inspirational leadership, and what makes some movements more successful than others. Guests include high school history teacher Diane Wolk-Rogers, writer and behavioral researcher Simon Sinek, 2016 Icelandic presidential candidate Halla Tómasdóttir, professor of leadership Jochen Menges, and writer and activist Naomi Klein.
Now Playing: Science for the People

#474 Appearance Matters
This week we talk about appearance, bodies, and body image. Why does what we look like affect our headspace so much? And how do we even begin to research a topic as personal and subjective as body image? To try and find out, we speak with some of the researchers at the Centre for Appearance Research (CAR) at the University of the West of England in Bristol. Psychology Professor Phillippa Diedrichs walks us through body image research, what we know so far, and how we know what we know. Professor of Appearance and Health Psychology Diana Harcourt talks about visible...