scholarly journals Persistent fluid flows defined by active matter boundaries

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Zijie Qu ◽  
Dominik Schildknecht ◽  
Shahriar Shadkhoo ◽  
Enrique Amaya ◽  
Jialong Jiang ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Protein Structures ◽  
Fluid Flows ◽  
Flow Fields ◽  
Self Organization ◽  
Force Model ◽  
Active Matter ◽  
Cytoskeletal Networks ◽  
Microtubule Networks ◽  
Protein Components

AbstractBiological systems control ambient fluids through the self-organization of active protein structures, including flagella, cilia, and cytoskeletal networks. Self-organization of protein components enables the control and modulation of fluid flow fields on micron scales, however, the physical principles underlying the organization and control of active-matter-driven fluid flows are poorly understood. Here, we use an optically-controlled active-matter system composed of microtubule filaments and light-switchable kinesin motor proteins to analyze the emergence of persistent flow fields. Using light, we form contractile microtubule networks of varying size and shape, and demonstrate that the geometry of microtubule flux at the corners of contracting microtubule networks predicts the architecture of fluid flow fields across network geometries through a simple point force model. Our work provides a foundation for programming microscopic fluid flows with controllable active matter and could enable the engineering of versatile and dynamic microfluidic devices.

scholarly journals Controlling Organization and Forces in Active Matter Through Optically-Defined Boundaries

2018 ◽  
Author(s):  
Tyler D. Ross ◽  
Heun Jin Lee ◽  
Zijie Qu ◽  
Rachel A. Banks ◽  
Rob Phillips ◽  
...  
Keyword(s):  
Fluid Flows ◽  
Cellular Structures ◽  
Active Matter ◽  
Experimental Systems ◽  
Order Of Magnitude ◽  
Equilibrium Structures ◽  
Microtubule Networks ◽  
Spatiotemporal Control ◽  
Individual Motor ◽  
Non Equilibrium

AbstractLiving systems are capable of locomotion, reconfiguration, and replication. To perform these tasks, cells spatiotemporally coordinate the interactions of force-generating, “active” molecules that create and manipulate non-equilibrium structures and force fields that span up to millimeter length scales [1–3]. Experimental active matter systems of biological or synthetic molecules are capable of spontaneously organizing into structures [4, 5] and generating global flows [6–9]. However, these experimental systems lack the spatiotemporal control found in cells, limiting their utility for studying non-equilibrium phenomena and bioinspired engineering. Here, we uncover non-equilibrium phenomena and principles by optically controlling structures and fluid flow in an engineered system of active biomolecules. Our engineered system consists of purified microtubules and light-activatable motor proteins that crosslink and organize microtubules into distinct structures upon illumination. We develop basic operations, defined as sets of light patterns, to create, move, and merge microtubule structures. By composing these basic operations, we are able to create microtubule networks that span several hundred microns in length and contract at speeds up to an order of magnitude faster than the speed of an individual motor. We manipulate these contractile networks to generate and sculpt persistent fluid flows. The principles of boundary-mediated control we uncover may be used to study emergent cellular structures and forces and to develop programmable active matter devices.

Lattice-BGK Methods for Simulating Incompressible Fluid Flows

1997 ◽  
Vol 08 (04) ◽  
pp. 793-803 ◽  
Author(s):  
Yu Chen ◽  
Hirotada Ohashi
Keyword(s):  
Fluid Flow ◽  
Incompressible Fluid ◽  
Poisson Equation ◽  
General Model ◽  
Incompressible Flows ◽  
Fluid Flows ◽  
Incompressible Limit ◽  
Numerical Example ◽  
Incompressible Fluid Flows

The lattice-Bhatnagar-Gross-Krook (BGK) method has been used to simulate fluid flow in the nearly incompressible limit. But for the completely incompressible flows, two special approaches should be applied to the general model, for the steady and unsteady cases, respectively. Introduced by Zou et al.,1 the method for steady incompressible flows will be described briefly in this paper. For the unsteady case, we will show, using a simple numerical example, the need to solve a Poisson equation for pressure.

A Suction Device Using Air Under Pressure

1956 ◽  
Vol 23 (2) ◽  
pp. 269-272
Author(s):  
L. F. Welanetz
Keyword(s):  
Fluid Flow ◽  
Flow Rate ◽  
Fluid Flows ◽  
Central Hole ◽  
Fluid Flow Rate ◽  
Circular Plates ◽  
Suction Device ◽  
Holding Power ◽  
Plate Separation

Abstract An analysis is made of the suction holding power of a device in which a fluid flows radially outward from a central hole between two parallel circular plates. The holding power and the fluid flow rate are determined as functions of the plate separation. The effect of changing the proportions of the device is investigated. Experiments were made to check the analysis.

scholarly journals Geometric Effect for Biological Reactors and Biological Fluids

2018 ◽  
Vol 5 (4) ◽  
pp. 110 ◽  
Author(s):  
Kazusa Beppu ◽  
Ziane Izri ◽  
Yusuke Maeda ◽  
Ryota Sakamoto
Keyword(s):  
Biological Fluids ◽  
Biological Systems ◽  
Self Organization ◽  
Active Matter ◽  
Confined Space ◽  
Self Organized ◽  
Motile Cells ◽  
Recent Developments ◽  
A Cell

As expressed “God made the bulk; the surface was invented by the devil” by W. Pauli, the surface has remarkable properties because broken symmetry in surface alters the material properties. In biological systems, the smallest functional and structural unit, which has a functional bulk space enclosed by a thin interface, is a cell. Cells contain inner cytosolic soup in which genetic information stored in DNA can be expressed through transcription (TX) and translation (TL). The exploration of cell-sized confinement has been recently investigated by using micron-scale droplets and microfluidic devices. In the first part of this review article, we describe recent developments of cell-free bioreactors where bacterial TX-TL machinery and DNA are encapsulated in these cell-sized compartments. Since synthetic biology and microfluidics meet toward the bottom-up assembly of cell-free bioreactors, the interplay between cellular geometry and TX-TL advances better control of biological structure and dynamics in vitro system. Furthermore, biological systems that show self-organization in confined space are not limited to a single cell, but are also involved in the collective behavior of motile cells, named active matter. In the second part, we describe recent studies where collectively ordered patterns of active matter, from bacterial suspensions to active cytoskeleton, are self-organized. Since geometry and topology are vital concepts to understand the ordered phase of active matter, a microfluidic device with designed compartments allows one to explore geometric principles behind self-organization across the molecular scale to cellular scale. Finally, we discuss the future perspectives of a microfluidic approach to explore the further understanding of biological systems from geometric and topological aspects.

scholarly journals Numerical Investigation on Fluid Flow in a 90-Degree Curved Pipe with Large Curvature Ratio

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Yan Wang ◽  
Quanlin Dong ◽  
Pengfei Wang
Keyword(s):  
Fluid Flow ◽  
Internal Flow ◽  
Fluid Flows ◽  
Detached Eddy Simulation ◽  
Number Range ◽  
Curvature Ratio ◽  
Large Curvature ◽  
Curved Pipe ◽  
Eddy Simulation ◽  
Curved Pipes

In order to understand the mechanism of fluid flows in curved pipes, a large number of theoretical and experimental researches have been performed. As a critical parameter of curved pipe, the curvature ratioδhas received much attention, but most of the values ofδare very small (δ<0.1) or relatively small (δ≤0.5). As a preliminary study and simulation this research studied the fluid flow in a 90-degree curved pipe of large curvature ratio. The Detached Eddy Simulation (DES) turbulence model was employed to investigate the fluid flows at the Reynolds number range from 5000 to 20000. After validation of the numerical strategy, the pressure and velocity distribution, pressure drop, fluid flow, and secondary flow along the curved pipe were illustrated. The results show that the fluid flow in a curved pipe with large curvature ratio seems to be unlike that in a curved pipe with small curvature ratio. Large curvature ratio makes the internal flow more complicated; thus, the flow patterns, the separation region, and the oscillatory flow are different.

Acoustic force model for the fluid flow under standing waves

2011 ◽  
Vol 72 (10) ◽  
pp. 754-759 ◽  
Author(s):  
Hong Lei ◽  
Daniel Henry ◽  
Hamda BenHadid
Keyword(s):  
Fluid Flow ◽  
Standing Waves ◽  
Force Model

A sliding mode estimation method for fluid flow fields using a differential inclusions-based analysis

2020 ◽  
pp. 1-10 ◽  
Author(s):  
Krishna Bhavithavya Kidambi ◽  
William MacKunis ◽  
Sergey V. Drakunov ◽  
Vladimir Golubev
Keyword(s):  
Fluid Flow ◽  
Differential Inclusions ◽  
Sliding Mode ◽  
Estimation Method ◽  
Flow Fields ◽  
Mode Estimation

scholarly journals Cytoskeleton in motion: the dynamics of keratin intermediate filaments in epithelia

2011 ◽  
Vol 194 (5) ◽  
pp. 669-678 ◽  
Author(s):  
Reinhard Windoffer ◽  
Michael Beil ◽  
Thomas M. Magin ◽  
Rudolf E. Leube
Keyword(s):  
Intermediate Filaments ◽  
Molecular Mechanisms ◽  
Protein Biosynthesis ◽  
Epithelial Tissue ◽  
Multistep Process ◽  
Keratin Filament ◽  
Cell Type Specific ◽  
Cytoskeletal Networks ◽  
Microtubule Networks ◽  
Keratin Intermediate Filaments

Epithelia are exposed to multiple forms of stress. Keratin intermediate filaments are abundant in epithelia and form cytoskeletal networks that contribute to cell type–specific functions, such as adhesion, migration, and metabolism. A perpetual keratin filament turnover cycle supports these functions. This multistep process keeps the cytoskeleton in motion, facilitating rapid and protein biosynthesis–independent network remodeling while maintaining an intact network. The current challenge is to unravel the molecular mechanisms underlying the regulation of the keratin cycle in relation to actin and microtubule networks and in the context of epithelial tissue function.

scholarly journals Computer Modeling of Electromagnetic Fields and Fluid Flows for Edge Containment in Continuous Casting

2004 ◽  
Vol 127 (4) ◽  
pp. 724-730 ◽  
Author(s):  
Fon-Chieh Chang ◽  
John R. Hull
Keyword(s):  
Numerical Simulation ◽  
Fluid Flow ◽  
Liquid Metal ◽  
Eddy Currents ◽  
Stokes Equations ◽  
Fluid Flows ◽  
Experimental Results ◽  
Twin Roll Casting ◽  
Roll Casting ◽  
Twin Roll

A computer model was developed to predict eddy currents and fluid flows in molten steel. The model was verified by comparing predictions with experimental results of liquid-metal containment and fluid flow in electromagnetic (EM) edge dams (EMDs) designed at Inland Steel (Ispat Industries Ltd.) for twin-roll casting. This mathematical model can greatly shorten casting research on the use of EM fields for liquid metal containment and control. It can also optimize the existing casting processes and minimize expensive, time-consuming full-scale testing. The model was verified by comparing predictions with experimental results of liquid metal containment and fluid flow in EM edge dams designed at Inland Steel (Ispat Industries Ltd.) for twin-roll casting. Numerical simulation was performed by coupling a three-dimensional (3D) finite-element EM code (ELEKTRA) and a 3D finite-difference fluids code (CaPS-EM) to solve Maxwell’s equations, Ohm’s law, Navier-Stokes equations, and transport equations of turbulence flow in a casting process that uses EM fields. ELEKTRA is able to predict the eddy-current distribution and EM forces in complex geometry. CaPS-EM is capable of modeling fluid flows with free surfaces and dynamic rollers. The computed 3D magnetic fields and induced eddy currents in ELEKTRA are used as input to flow-field computations in CaPS-EM. Results of the numerical simulation compared well with measurements obtained from both static and dynamic tests.

scholarly journals Disks aligned in a turbulent channel

2015 ◽  
Vol 772 ◽  
pp. 1-4 ◽  
Author(s):  
Greg A. Voth
Keyword(s):  
Fluid Flow ◽  
Channel Flow ◽  
Particle Shape ◽  
Particle Density ◽  
Biological Fluid ◽  
Fluid Flows ◽  
Turbulent Channel Flow ◽  
Anisotropic Particles ◽  
Wide Range ◽  
Preferential Alignment

Anisotropic particles are suspended in a wide range of industrial, environmental and biological fluid flows. The orientations of these particles are sometimes randomized by turbulence, but often they are brought into preferential alignment by the fluid flow. In a recently published study, Challabotla, Zhao & Andersson (J. Fluid Mech., vol. 766, 2015, R2) performed the first numerical simulations of inertial disks in a turbulent channel flow. They find that disks can be made to preferentially align either parallel or perpendicular to the wall depending on the particle density. Particle shape also affects alignment, particularly for lower density particles, and the alignment of disks is quite different from the alignment of fibres.

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