HSE Scientist Optimises Solution of Hydrodynamics Problems
Supercomputers are no longer required to calculate fluid flows in multiscale problems.
Roman Gaydukov, Associate Professor at the MIEM HSE School of Applied Mathematics, has modelled the fluid flow around a rotating disk with small surface irregularities. His solution allows for predicting fluid flow behaviour without the need for powerful supercomputers. The results have been published in Russian Journal of Mathematical Physics.
Hydrodynamics studies the motion of fluids and their interaction with solid surfaces. This branch of physics makes it possible to understand and predict the behaviour of fluids and gases under various conditions. In particular, the principles of hydrodynamics are used in electrochemistry for calculating the reactions of galvanisation, such as silver molecules adhering to a metal surface, and oxidation, such as patina formation on copper.
These processes use a disk electrode, which is a flat metal plate that rotates in a fluid. To accurately calculate electrochemical reactions, it is essential to understand how the fluid moves around the electrode and what conditions that need to be maintained. To achieve this, scientists must account for numerous variables, while even minor irregularities on the disk surface can greatly influence fluid flow, leading to complex and unexpected effects.
Earlier studies focused solely on symmetrical irregularities, but a scientist at HSE University examined a more complex case. Roman Gaydukov calculated how fluid flow would change with the presence of asymmetrical irregularities on the rotating disk surface.
To do this, he used the method of multideck structures of boundary layers, making it possible to decompose the three-dimensional problem into a series of two-dimensional ones. This method helps solve complex hydrodynamic problems at high Reynolds numbers, where direct modelling is impossible. Although this method has been known since the late 1960s, a rigorous mathematical formulation was only recently developed by the author of the paper together with Professor Vladimir Danilov. The mathematical algorithm of the method can be integrated into any symbolic computation software.
Roman Gaydukov
'Under real conditions, perfectly smooth surfaces do not exist. We have demonstrated how small irregularities on the disk surface affect fluid flow by creating vortex zones and altering the structure of the boundary layer,' explains Roman Gaydukov. 'Our method allows modelling a problem within a few hours, whereas it could take days or even weeks on a supercomputer. This not only saves time but also reduces the cost of computational resources. The method works effectively for large but finite Reynolds numbers.'
The Reynolds number is a dimensionless quantity that describes the relationship between inertial and viscous forces in fluid flow. A large Reynolds number signifies the dominance of inertial forces, which often results in turbulent (chaotic) flows, while a small Reynolds number indicates the dominance of viscous forces, leading to laminar (ordered) flows.
The developed approach can be used to accurately model fluid motion during chemical reactions, with potentially wide applications in industry.
In the future, the scientist plans to extend his research to more complex systems involving interactions between different phases, such as liquid droplets in an air stream or aerosols. This will enable a deeper understanding of the processes in multicomponent and multiphase systems and help improve existing models.
According to Gaydukov, 'Together with my graduate student Nikita Burov, we plan to investigate how the shape of fluid droplets changes as they move through an air flow and how the droplets, as irregularities—including their potential freezing—affect the flow.'
See also:
Esports Players Play Better Online
In competitions, esports players, like other athletes, face stress and show worse results due to pressure. A substantial decrease takes place in the performance of esports players during overtime. This effect, however, is significantly mitigated in online competitions compared to live events—the difference can reach 30%. A study by a team of authors from HSE University’s Moscow and Perm campuses and European University Viadrina (Germany) explores the phenomenon of choking under pressure within the context of esports. The study was published in the Journal of Economic Behavior & Organization.
Analysing Genetic Information Can Help Prevent Complications after Myocardial Infarction
Researchers at HSE University have developed a machine learning (ML) model capable of predicting the risk of complications—major adverse cardiac events—in patients following a myocardial infarction. For the first time, the model incorporates genetic data, enabling a more accurate assessment of the risk of long-term complications. The study has been published in Frontiers in Medicine.
A New Tool Designed to Assess AI Ethics in Medicine Developed at HSE University
A team of researchers at the HSE AI Research Centre has created an index to evaluate the ethical standards of artificial intelligence (AI) systems used in medicine. This tool is designed to minimise potential risks and promote safer development and implementation of AI technologies in medical practice.
Smoking Habit Affects Response to False Feedback
A team of scientists at HSE University, in collaboration with the Institute of Higher Nervous Activity and Neurophysiology of the Russian Academy of Sciences, studied how people respond to deception when under stress and cognitive load. The study revealed that smoking habits interfere with performance on cognitive tasks involving memory and attention and impairs a person’s ability to detect deception. The study findings have been published in Frontiers in Neuroscience.
Russian Physicists Determine Indices Enabling Prediction of Laser Behaviour
Russian scientists, including researchers at HSE University, examined the features of fibre laser generation and identified universal critical indices for calculating their characteristics and operating regimes. The study findings will help predict and optimise laser parameters for high-speed communication systems, spectroscopy, and other areas of optical technology. The paper has been published in Optics & Laser Technology.
Children with Autism Process Auditory Information Differently
A team of scientists, including researchers from the HSE Centre for Language and Brain, examined specific aspects of auditory perception in children with autism. The scientists observed atypical alpha rhythm activity both during sound perception and at rest. This suggests that these children experience abnormalities in the early stages of sound processing in the brain's auditory cortex. Over time, these abnormalities can result in language difficulties. The study findings have been published in Brain Structure and Function.
Smartphones Not Used for Digital Learning among Russian School Students
Despite the widespread use of smartphones, teachers have not fully integrated them into the teaching and learning process, including for developing students' digital skills. Irina Dvoretskaya, Research Fellow at the HSE Institute of Education, has examined the patterns of mobile device use for learning among students in grades 9 to 11.
Working while Studying Can Increase Salary and Chances of Success
Research shows that working while studying increases the likelihood of employment after graduation by 19% and boosts salary by 14%. One in two students has worked for at least a month while studying full time. The greatest benefits come from being employed during the final years of study, when students have the opportunity to begin working in their chosen field. These findings come from a team of authors at the HSE Faculty of Economic Sciences.
Beauty in Details: HSE University and AIRI Scientists Develop a Method for High-Quality Image Editing
Researchers from theHSE AI Research Centre, AIRI, and the University of Bremen have developed a new image editing method based on deep learning—StyleFeatureEditor. This tool allows for precise reproduction of even the smallest details in an image while preserving them during the editing process. With its help, users can easily change hair colour or facial expressions without sacrificing image quality. The results of this three-party collaboration were published at the highly-cited computer vision conference CVPR 2024.
HSE Scientists Have Examined Potential Impact of Nuclear Power on Sustainable Development
Researchers at HSE University have developed a set of mathematical models to predict the impact of nuclear power on the Sustainable Development Index. If the share of nuclear power in the global energy mix increases to between 20% and 25%, the global Sustainable Development Index (SDI) is projected to grow by one-third by 2050. In scenarios where the share of nuclear power grows more slowly, the increase in the SDI is found to be lower. The study has been published in Nuclear Energy and Technology.