Mean-field-based Lagrangian framework is developed for the fluid turbulence theory, which enables physically objective discussions, especially, of the history effect. Mean flow serves as a purely geometrical object of Lie group theory, providing useful operations to measure the objective rate and history integration of the general tensor field. The proposed framework is applied, on the one hand, to one-point closure model, yielding an objective expression of the turbulence viscoelastic effect. Application to two-point closure, on the other hand, is also discussed, where natural extension of known Lagrangian correlation is discovered on the basis of an extended covariance group.
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http://dx.doi.org/10.1103/PhysRevE.95.053102 | DOI Listing |
Heliyon
January 2025
Department of Mechanical Engineering, Central Tehran Branch, Islamic Azad University, Tehran, Iran.
Background: The development of heat transfer devices used for heat conversion and recovery in several industrial and residential applications has long focused on improving heat transfer between two parallel plates. Numerous articles have examined the relevance of enhancing thermal performance for the system's performance and economics. Heat transport is improved by increasing the Reynolds number as the turbulent effects grow.
View Article and Find Full Text PDFWater Sci Technol
January 2025
Chair of Water Resources Management and Modeling of Hydrosystems, Technische Universität Berlin, Gustav-Meyer-Allee 25, Berlin 13355, Germany.
This study explores the computational fluid dynamics (CFD) simulation of oxygen (O) and hydrogen sulfide (HS) mass transfer in a highly turbulent stirring tank. Using the open-source software OpenFOAM, we extended three-dimensional two-phase flow solvers with a rotating mesh feature to model the mass transfer processes between the water and air phases. The accuracy of these simulations was validated against experimental data, demonstrating a strong agreement in the mass transfer rates of HS and O.
View Article and Find Full Text PDFInt J Pharm
January 2025
SSPC Research Centre, Department of Chemical Sciences & Chemical Engineering, Bernal Institute, University of Limerick, Limerick V94 T9PX Ireland. Electronic address:
Atomization-based techniques are widely used in pharmaceutical industry for production of fine drug particles due to their versatility and adaptability. Key performance measure of such techniques is their ability to provide control over critical quality attributes (CQAs) of produced drug particles. CQAs of drug particles produced via atomization critically depend on fluid dynamics of sprays; resulting mixing, heat and mass transfer; distribution of supersaturation and subsequent nucleation and growth of particles.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
January 2025
Center for Complexity and Biosystems, Department of Environmental Science and Policy, University of Milan, 20133 Milan, Italy.
Collective migration of cancer cells is often interpreted using concepts derived from the physics of active matter, but the experimental evidence is mostly restricted to observations made in vitro. Here, we study collective invasion of metastatic cancer cells injected into the mouse deep dermis using intravital multiphoton microscopy combined with a skin window technique and three-dimensional quantitative image analysis. We observe a multicellular but low-cohesive migration mode characterized by rotational patterns which self-organize into antiparallel persistent tracks with orientational nematic order.
View Article and Find Full Text PDFJ Biomech Eng
January 2025
Department of Mechanical Engineering Marshall University, Huntington, WV 25755, USA; Department of Biomedical Engineering Marshall University, Huntington, WV 25755, USA.
Cell-laden, scaffold-based tissue engineering methods have been successfully utilized for the treatment of bone fractures. In such methods, the rate of scaffold biodegradation, transport of nutrients, and removal of cell metabolic wastes are critical fluid-dynamics factors, affecting tissue regeneration. Therefore, there is a critical need to identify the underlying material transport mechanisms associated with stem cell-driven, scaffold-based bone tissue regeneration.
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