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Ramin Golestanian - One of the best experts on this subject based on the ideXlab platform.
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Stochastic Low Reynolds Number swimmers
Journal of Physics: Condensed Matter, 2009Co-Authors: Ramin Golestanian, Armand AjdariAbstract:As technological advances alLow us to fabricate smaller autonomous self-propelled devices, it is clear that at some point directed propulsion could not come from pre-specified deterministic periodic deformation of the swimmer's body and we need to develop strategies for extracting a net directed motion from a series of random transitions in the conformation space of the swimmer. We present a theoretical formulation for describing the 'stochastic motor' that drives the motion of Low Reynolds Number swimmers based on this concept, and use it to study the propulsion of a simple Low Reynolds Number swimmer, namely, the three-sphere swimmer model. When the detailed balanced is broken and the motor is driven out of equilibrium, it can propel the swimmer in the required direction. The formulation can be used to study optimal design strategies for molecular scale Low Reynolds Number swimmers.
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Stochastic Low Reynolds Number Swimmers
Journal of physics. Condensed matter : an Institute of Physics journal, 2009Co-Authors: Ramin Golestanian, Armand AjdariAbstract:As technological advances alLow us to fabricate smaller autonomous self-propelled devices, it is clear that at some point directed propulsion could not come from pre-specified deterministic periodic deformation of the swimmer's body and we need to develop strategies to extract a net directed motion from a series of random transitions in the conformation space of the swimmer. We present a theoretical formulation to describe the "stochastic motor" that drives the motion of Low Reynolds Number swimmers based on this concept, and use it to study the propulsion of a simple Low Reynolds Number swimmer, namely, the three-sphere swimmer model. When the detailed-balanced is broken and the motor is driven out of equilibrium, it can propel the swimmer in the required direction. The formulation can be used to study optimal design strategies for molecular-scale Low Reynolds Number swimmers.
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Propulsion at Low Reynolds Number
Journal of Physics: Condensed Matter, 2005Co-Authors: Ali Najafi, Ramin GolestanianAbstract:We study the propulsion of two model swimmers at Low Reynolds Number. Inspired by Purcell's model, we propose a very simple one-dimensional swimmer consisting of three spheres that are connected by two arms whose lengths can change between two values. The proposed swimmer can swim with a special type of motion, which breaks the time-reversal symmetry. We also show that an ellipsoidal membrane with tangential travelling wave on it can also propel itself in the direction preferred by the travelling wave. This system resembles the realistic biological animals like Paramecium.
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simple swimmer at Low Reynolds Number three linked spheres
Physical Review E, 2004Co-Authors: Ali Najafi, Ramin GolestanianAbstract:We propose a very simple one-dimensional swimmer consisting of three spheres that are linked by rigid rods whose lengths can change between two values. With a periodic motion in a nonreciprocal fashion, which breaks the time-reversal symmetry as well as the translational symmetry, we show that the model device can swim at Low Reynolds Number. This model system could be used in constructing molecular-sized machines.
Zhuyi - One of the best experts on this subject based on the ideXlab platform.
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Modeling Low Reynolds Number Incompressible FLows Using SPH
Journal of Computational Physics, 1997Co-Authors: P Morrisjoseph, J Foxpatrick, ZhuyiAbstract:The method of smoothed particle hydrodynamics (SPH) is extended to model incompressible fLows of Low Reynolds Number. For such fLows, modification of the standard SPH formalism is required to minim...
Julia M. Yeomans - One of the best experts on this subject based on the ideXlab platform.
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A circle swimmer at Low Reynolds Number
arXiv: Soft Condensed Matter, 2012Co-Authors: Rodrigo Ledesma-aguilar, Hartmut Loewen, Julia M. YeomansAbstract:Swimming in circles occurs in a variety of situations at Low Reynolds Number. Here we propose a simple model for a swimmer that undergoes circular motion, generalising the model of a linear swimmer proposed by Najafi and Golestanian (Phys. Rev. E 69, 062901 (2004)). Our model consists of three solid spheres arranged in a triangular configuration, joined by two links of time-dependent length. For small strokes, we discuss the motion of the swimmer as a function of the separation angle between its links. We find that swimmers describe either clockwise or anticlockwise circular motion depending on the tilting angle in a non-trivial manner. The symmetry of the swimmer leads to a quadrupolar decay of the far fLow field. We discuss the potential extensions and experimental realisation of our model.
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Hydrodynamic Interactions at Low Reynolds Number
Experimental Mechanics, 2010Co-Authors: G. P. Alexander, Julia M. YeomansAbstract:We consider the hydrodynamic interactions of Low Reynolds Number microswimmers, presenting a review of recent work based upon models of linked sphere swimmers. Particular attention is paid to those aspects that are generic, applicable to all microswimmers and not only to the simple models considered. The importance of the relative phase in swimmer–swimmer interactions is emphasised, as is the role of simple symmetry arguments in both understanding and constraining the hydrodynamic properties of microswimmers.
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Scattering of Low-Reynolds-Number swimmers.
Physical Review E, 2008Co-Authors: G. P. Alexander, C. M. Pooley, Julia M. YeomansAbstract:We describe the consequences of time-reversal invariance of the Stokes equations for the hydrodynamic scattering of two Low-Reynolds-Number swimmers. For swimmers that are related to each other by a time-reversal transformation, this leads to the striking result that the angle between the two swimmers is preserved by the scattering. The result is illustrated for the particular case of a linked-sphere model swimmer. For more general pairs of swimmers, not related to each other by time reversal, we find that hydrodynamic scattering can alter the angle between their trajectories by several tens of degrees. For two identical contractile swimmers, this can lead to the formation of a bound state.
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Modeling microscopic swimmers at Low Reynolds Number.
The Journal of chemical physics, 2007Co-Authors: David J. Earl, C. M. Pooley, J. F. Ryder, Irene Bredberg, Julia M. YeomansAbstract:The authors employ three numerical methods to explore the motion of Low Reynolds Number swimmers, modeling the hydrodynamic interactions by means of the Oseen tensor approximation, lattice Boltzmann simulations, and multiparticle collision dynamics. By applying the methods to a three bead linear swimmer, for which exact results are known, the authors are able to compare and assess the effectiveness of the different approaches. They then propose a new class of Low Reynolds Number swimmers, generalized three bead swimmers that can change both the length of their arms and the angle between them. Hence they suggest a design for a microstructure capable of moving in three dimensions. They discuss multiple bead, linear microstructures and show that they are highly efficient swimmers. They then turn to consider the swimming motion of elastic filaments. Using multiparticle collision dynamics the authors show that a driven filament behaves in a qualitatively similar way to the micron-scale swimming device recently...
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Modeling microscopic swimmers at Low Reynolds Number
arXiv: Soft Condensed Matter, 2007Co-Authors: David J. Earl, C. M. Pooley, J. F. Ryder, Irene Bredberg, Julia M. YeomansAbstract:We employ three numerical methods to explore the motion of Low Reynolds Number swimmers, modeling the hydrodynamic interactions by means of the Oseen tensor approximation, lattice Boltzmann simulations and multiparticle collision dynamics. By applying the methods to a three bead linear swimmer, for which exact results are known, we are able to compare and assess the effectiveness of the different approaches. We then propose a new class of Low Reynolds Number swimmers, generalized three bead swimmers that can change both the length of their arms and the angle between them. Hence we suggest a design for a microstructure capable of moving in three dimensions. We discuss multiple bead, linear microstructures and show that they are highly efficient swimmers. We then turn to consider the swimming motion of elastic filaments. Using multiparticle collision dynamics we show that a driven filament behaves in a qualitatively similar way to the micron-scale swimming device recently demonstrated by Dreyfus et al.
P Morrisjoseph - One of the best experts on this subject based on the ideXlab platform.
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Modeling Low Reynolds Number Incompressible FLows Using SPH
Journal of Computational Physics, 1997Co-Authors: P Morrisjoseph, J Foxpatrick, ZhuyiAbstract:The method of smoothed particle hydrodynamics (SPH) is extended to model incompressible fLows of Low Reynolds Number. For such fLows, modification of the standard SPH formalism is required to minim...
John F. Brady - One of the best experts on this subject based on the ideXlab platform.
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Many-body effects and matrix inversion in Low-Reynolds-Number hydrodynamics
Physics of Fluids, 2001Co-Authors: Kengo Ichiki, John F. BradyAbstract:It is shown that the method of reflections in resistance form (with truncated multipoles) is one of many possible iterative methods to obtain the inverse of the mobility matrix (with the same truncation) in Low-Reynolds-Number hydrodynamics. Although the method of reflections in the mobility form is guaranteed to converge, it is found that in the resistance form the method may fail to converge. This breakdown is overcome by conjugate-gradient-type iterative methods, and the implications of the iterative method for Low-Reynolds-Number hydrodynamics are discussed.
