On the role of helicity in complex fluid flows

1985 ◽  
Vol 113 (1) ◽  
pp. 32-37 ◽  
Author(s):  
Leonid Shtilman ◽  
Evgeny Levich ◽  
Steven A. Orszag ◽  
Richard B. Pelz ◽  
Arkady Tsinober
Keyword(s):  
Fluid Flows ◽  
Complex Fluid

Role of Reynolds and Archimedes numbers in particle-fluid flows

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Haim Kalman
Keyword(s):  
Flow Regime ◽  
Power Function ◽  
Fluid Flows ◽  
Limited Range ◽  
Operating Conditions ◽  
Pneumatic Conveying ◽  
Particulate Materials ◽  
Simple Power ◽  
Simple Power Function

AbstractAny scientific behavior is best represented by nondimensional numbers. However, in many cases, for pneumatic conveying systems, dimensional equations are developed and used. In some cases, many of the nondimensional equations include Reynolds (Re) and Froude (Fr) numbers; they are usually defined for a limited range of materials and operating conditions. This study demonstrates that most of the relevant flow types, whether in horizontal or vertical pipes, can be better described by Re and Archimedes (Ar) numbers. Ar can also be used in hydraulic conveying systems. This paper presents many threshold velocities that are accurately defined by Re as a simple power function of Ar. Many particulate materials are considered by Ar, thereby linking them to a common behavior. Using various threshold velocities, a flow regime chart for horizontal conveying is presented in this paper.

scholarly journals The effects of luminal and trans-endothelial fluid flows on the extravasation and tissue invasion of tumor cells in a 3D in vitro microvascular platform

2020 ◽  
Author(s):  
Cynthia Hajal ◽  
Lina Ibrahim ◽  
Jean Carlos Serrano ◽  
Giovanni S. Offeddu ◽  
Roger D. Kamm
Keyword(s):  
Tumor Cells ◽  
Fluid Flows ◽  
Metastatic Potential ◽  
Migration Speed ◽  
Close Proximity ◽  
The Matrix ◽  
Luminal Flow ◽  
Complex Fluid ◽  
Key Steps

ABSTRACTThroughout the process of metastatic dissemination, tumor cells are continuously subjected to mechanical forces resulting from complex fluid flows due to changes in pressures in their local microenvironments. While these forces have been associated with invasive phenotypes in 3D matrices, their role in key steps of the metastatic cascade, namely extravasation and subsequent interstitial migration, remains poorly understood. In this study, an in vitro model of the human microvasculature was employed to subject tumor cells to physiological luminal, trans-endothelial, and interstitial flows to evaluate their effects on those key steps of metastasis. Luminal flow promoted the extravasation potential of tumor cells, possibly as a result of their increased intravascular migration speed. Trans-endothelial flow increased the speed with which tumor cells transmigrated across the endothelium as well as their migration speed in the matrix following extravasation. In addition, tumor cells possessed a greater propensity to migrate in close proximity to the endothelium when subjected to physiological flows, which may promote the successful formation of metastatic foci. These results show important roles of fluid flow during extravasation and invasion, which could determine the local metastatic potential of tumor cells.

scholarly journals Deep learning in fluid dynamics

2017 ◽  
Vol 814 ◽  
pp. 1-4 ◽  
Author(s):  
J. Nathan Kutz
Keyword(s):  
Neural Networks ◽  
Deep Learning ◽  
Turbulence Models ◽  
Fluid Flows ◽  
Navier Stokes ◽  
Complex Flows ◽  
Big Data Applications ◽  
Complex Fluid ◽  
Mining Tool ◽  
Performance Gains

It was only a matter of time before deep neural networks (DNNs) – deep learning – made their mark in turbulence modelling, or more broadly, in the general area of high-dimensional, complex dynamical systems. In the last decade, DNNs have become a dominant data mining tool for big data applications. Although neural networks have been applied previously to complex fluid flows, the article featured here (Ling et al., J. Fluid Mech., vol. 807, 2016, pp. 155–166) is the first to apply a true DNN architecture, specifically to Reynolds averaged Navier Stokes turbulence models. As one often expects with modern DNNs, performance gains are achieved over competing state-of-the-art methods, suggesting that DNNs may play a critically enabling role in the future of modelling complex flows.

Fight the flow: the role of shear in artificial rheotaxis for individual and collective motion

Nanoscale ◽  
2019 ◽  
Vol 11 (22) ◽  
pp. 10944-10951 ◽  
Author(s):  
Remmi Baker ◽  
Joshua E. Kauffman ◽  
Abhrajit Laskar ◽  
Oleg E. Shklyaev ◽  
Mykhailo Potomkin ◽  
...  
Keyword(s):  
Collective Motion ◽  
Complex Fluid

To navigate in complex fluid environments, swimming organisms like fish or bacteria often reorient their bodies antiparallel or against the flow, more commonly known as rheotaxis.

Role of dynamic water rivulets in the excitation of rain–wind-induced cable vibration: A critical review

2021 ◽  
pp. 136943322110401
Author(s):  
Donglai Gao ◽  
Wenjie Li ◽  
Haiquan Jing ◽  
Jian Wang ◽  
Jintuan Wu ◽  
...  
Keyword(s):  
Wind Engineering ◽  
Excitation Mechanism ◽  
Structure Interaction ◽  
Wall Boundary Layer ◽  
Stay Cables ◽  
Considerable Research ◽  
Complex Fluid ◽  
Wind Induced Vibration ◽  
Cable Stayed Bridges

It has been more than 30 years since Hikami Y and Shiraishi N (1988) Rain–wind-induced vibrations of cable-stayed bridges. Journal of Wind Engineering and Industrial Aerodynamics 29: 409–418 first reported the rain–wind-induced vibration (RWIV) of stay cables in the construction stage of Meikonishi Bridge, Japan. After that, considerable research efforts have been devoted to understanding the RWIV of stay cables, and the role of the upper rivulet has been gradually realized and studied. This study presents a selective review on recent progress of RWIV and its controversial excitation mechanism. The available knowledge and up-to-date understanding of this complex fluid-structure interaction are presented in some detail. The formation, dynamics of water rivulet, and its role in affecting the near-wall boundary layer properties and in the excitation scenario of RWIV are of particular interest in this study. Finally, some limitations of previous studies are concluded, with some perspective suggestions for further study of excitation mechanism of RWIV.

The Segregated Approach to Predicting Viscous Compressible Fluid Flows

1987 ◽  
Vol 109 (2) ◽  
pp. 268-277 ◽  
Author(s):  
J. P. Van Doormaal ◽  
G. D. Raithby ◽  
B. H. McDonald
Keyword(s):  
Numerical Method ◽  
Compressible Fluid ◽  
Equations Of Motion ◽  
Fluid Flows ◽  
Mass Conservation ◽  
Viscous Compressible Fluid ◽  
Algebraic Equations ◽  
Simple Method ◽  
Compressible Fluid Flows

The SIMPLE method of Patankar and Spalding and its variants such as SIMPLER, SIMPLEC, and SIMPLEX are segregated methods for solving the discrete algebraic equations representing the equations of motion for an incompressible fluid flow. The present paper presents the extension of these methods to the solution of compressible fluid flows within the context of generalized segregated approach. To provide a framework for better understanding the segregated approach to solving viscous compressible fluid flows an interpretation of the role of pressure in the numerical method is presented. With this interpretation it becomes evident that the linearization of the equation for mass conservation and the approach used to solve the linearized algebraic equations representing the equations of motion are important in determining the performance of the numerical method. The relative performances of the various segregated methods are compared for several subsonic and supersonic compressible fluid flows.

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