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Malm AV, Waigh TA. Elastic turbulence in entangled semi-dilute DNA solutions measured with optical coherence tomography velocimetry. Sci Rep 2017; 7:1186. [PMID: 28442789 PMCID: PMC5430809 DOI: 10.1038/s41598-017-01303-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 03/29/2017] [Indexed: 12/11/2022] Open
Abstract
The flow instabilities of solutions of high molecular weight DNA in the entangled semi-dilute concentration regime were investigated using optical coherence tomography velocimetry, a technique that provides high spatial (probe volumes of 3.4 pL) and temporal resolution (sub μs) information on the flow behaviour of complex fluids in a rheometer. The velocity profiles of the opaque DNA solutions (high and low salt) were measured as a function of the distance across the gap of a parallel plate rheometer, and their evolution over time was measured. At lower DNA concentrations and low shear rates, the velocity fluctuations were well described by Gaussian functions and the velocity gradient was uniform across the rheometer gap, which is expected for Newtonian flows. As the DNA concentration and shear rate were increased there was a stable wall slip regime followed by an evolving wall slip regime, which is finally followed by the onset of elastic turbulence. Strain localization (shear banding) is observed on the boundaries of the flows at intermediate shear rates, but decreases in the high shear elastic turbulence regime, where bulk strain localization occurs. A dynamic phase diagram for non-linear flow was created to describe the different behaviours.
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Affiliation(s)
- A V Malm
- Biological Physics, School of Physics and Astronomy, University of Manchester, Oxford Rd., Manchester, M13 9PL, UK.,Photon Science Institute, University of Manchester, Oxford Rd., Manchester, M13 9PL, UK
| | - T A Waigh
- Biological Physics, School of Physics and Astronomy, University of Manchester, Oxford Rd., Manchester, M13 9PL, UK. .,Photon Science Institute, University of Manchester, Oxford Rd., Manchester, M13 9PL, UK.
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Schwabe M, Zhdanov S, Räth C, Graves DB, Thomas HM, Morfill GE. Collective effects in vortex movements in complex plasmas. PHYSICAL REVIEW LETTERS 2014; 112:115002. [PMID: 24702381 DOI: 10.1103/physrevlett.112.115002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Indexed: 06/03/2023]
Abstract
We study the onset and characteristics of vortices in complex (dusty) plasmas using two-dimensional simulations in a setup modeled after the PK-3 Plus laboratory. A small number of microparticles initially self-arranges in a monolayer around the void. As additional particles are introduced, an extended system of vortices develops due to a nonzero curl of the plasma forces. We demonstrate a shear-thinning effect in the vortices. Velocity structure functions and the energy and enstrophy spectra show that vortex flow turbulence is present that is in essence of the "classical" Kolmogorov type.
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Affiliation(s)
- Mierk Schwabe
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, USA and Max Planck Institute for Extraterrestrial Physics, P.O. Box 1312, Giessenbachstraße, 85741 Garching, Germany
| | - Sergey Zhdanov
- Max Planck Institute for Extraterrestrial Physics, P.O. Box 1312, Giessenbachstraße, 85741 Garching, Germany
| | - Christoph Räth
- Max Planck Institute for Extraterrestrial Physics, P.O. Box 1312, Giessenbachstraße, 85741 Garching, Germany
| | - David B Graves
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California 94720, USA
| | - Hubertus M Thomas
- Max Planck Institute for Extraterrestrial Physics, P.O. Box 1312, Giessenbachstraße, 85741 Garching, Germany
| | - Gregor E Morfill
- Max Planck Institute for Extraterrestrial Physics, P.O. Box 1312, Giessenbachstraße, 85741 Garching, Germany
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Wensink HH, Dunkel J, Heidenreich S, Drescher K, Goldstein RE, Löwen H, Yeomans JM. Meso-scale turbulence in living fluids. Proc Natl Acad Sci U S A 2012; 109:14308-13. [PMID: 22908244 PMCID: PMC3437854 DOI: 10.1073/pnas.1202032109] [Citation(s) in RCA: 458] [Impact Index Per Article: 38.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Turbulence is ubiquitous, from oceanic currents to small-scale biological and quantum systems. Self-sustained turbulent motion in microbial suspensions presents an intriguing example of collective dynamical behavior among the simplest forms of life and is important for fluid mixing and molecular transport on the microscale. The mathematical characterization of turbulence phenomena in active nonequilibrium fluids proves even more difficult than for conventional liquids or gases. It is not known which features of turbulent phases in living matter are universal or system-specific or which generalizations of the Navier-Stokes equations are able to describe them adequately. Here, we combine experiments, particle simulations, and continuum theory to identify the statistical properties of self-sustained meso-scale turbulence in active systems. To study how dimensionality and boundary conditions affect collective bacterial dynamics, we measured energy spectra and structure functions in dense Bacillus subtilis suspensions in quasi-2D and 3D geometries. Our experimental results for the bacterial flow statistics agree well with predictions from a minimal model for self-propelled rods, suggesting that at high concentrations the collective motion of the bacteria is dominated by short-range interactions. To provide a basis for future theoretical studies, we propose a minimal continuum model for incompressible bacterial flow. A detailed numerical analysis of the 2D case shows that this theory can reproduce many of the experimentally observed features of self-sustained active turbulence.
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Affiliation(s)
- Henricus H. Wensink
- Institute for Theoretical Physics II: Soft Matter, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, D-40225 Düsseldorf, Germany
- Laboratoire de Physique des Solides, Université Paris-Sud 11, Bâtiment 510, 91405 Orsay Cedex, France
| | - Jörn Dunkel
- DAMTP, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, United Kingdom
| | | | - Knut Drescher
- DAMTP, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, United Kingdom
- Departments of Molecular Biology and Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544; and
| | - Raymond E. Goldstein
- DAMTP, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, United Kingdom
| | - Hartmut Löwen
- Institute for Theoretical Physics II: Soft Matter, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, D-40225 Düsseldorf, Germany
| | - Julia M. Yeomans
- Rudolf Peierls Centre for Theoretical Physics, University of Oxford, 1 Keble Road, Oxford OX1 3NP, United Kingdom
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Klapp SHL, Hess S. Shear-stress-controlled dynamics of nematic complex fluids. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 81:051711. [PMID: 20866251 DOI: 10.1103/physreve.81.051711] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2010] [Indexed: 05/29/2023]
Abstract
Based on a mesoscopic theory we investigate the nonequilibrium dynamics of a sheared nematic liquid, with the control parameter being the shear stress σ xy (rather than the usual shear rate, γ). To this end we supplement the equations of motion for the orientational order parameters by an equation for γ, which then becomes time dependent. Shearing the system from an isotropic state, the stress-controlled flow properties turn out to be essentially identical to those at fixed γ. Pronounced differences occur when the equilibrium state is nematic. Here, shearing at controlled γ yields several nonequilibrium transitions between different dynamic states, including chaotic regimes. The corresponding stress-controlled system has only one transition from a regular periodic into a stationary (shear-aligned) state. The position of this transition in the σ xy-γ plane turns out to be tunable by the delay time entering our control scheme for σ xy. Moreover, a sudden change in the control method can stabilize the chaotic states appearing at fixed γ.
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Affiliation(s)
- Sabine H L Klapp
- Institut für Theoretische Physik, Sekretariat EW 7-1, Technische Universität Berlin, Hardenbergstrasse 36, D-10623 Berlin, Germany
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