Reinforcement Learning and Wavelet Adapted Vortex Methods for Simulations of Self-propelled Swimmers

Gazzola, Mattia; Hejazialhosseini, Babak; Koumoutsakos, Petros

doi:10.1137/130943078

Cited by 107 publications

(81 citation statements)

References 51 publications

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“…This system of equations is solved in the velocity-vorticity form by combining remeshed vortex methods with Brinkmann penalization and a projection approach [54]. This method has been extensively validated across a range of biophysical problems, from bluff body flows to biological swimming [23,[54][55][56].…”

Section: Governing Equations Numerical Methods and Validationmentioning

confidence: 99%

Streaming-enhanced flow-mediated transport

2019

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We investigate the capability of an active body (master) to manipulate a passive object (slave) purely via contactless flow-mediated mechanisms, motivated by potential applications in microfluidic devices and medicine (drug delivery purposes). We extend prior works on active-passive cylinder pairs by superimposing periodic oscillations to the master's linear motion. In a viscous fluid, such oscillations produce an additional viscous streaming field, which is leveraged for enhancing slave transport. We see that superimposing oscillations robustly improves transport across a range of Reynolds numbers. Comparison with results without oscillations highlights the flow mechanisms at work, which we capitalize on to design (master) geometries for augmented transport. These principles are found to extend to three-dimensional active-passive shapes as well. * Electronic address: mgazzola@illinois.edu arXiv:1809.04566v1 [physics.flu-dyn]

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Section: Governing Equations Numerical Methods and Validationmentioning

confidence: 99%

Streaming-enhanced flow-mediated transport

2019

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“…This allows users to formulate simulations without the need of explicitly interacting with a highly sophisticated spatiotemporally-adaptive machinery. The present software have been used for the simulations of bluff body flows [23], flow-mediated interactions between two cylinders [24], for the analysis of optimal shapes in anguilliform swimming at intermediated Reynolds numbers [25], and the investigation of reinforcement learning within the context of self-propelled bodies [26].…”

Section: Introductionmentioning

confidence: 99%

MRAG-I2D: Multi-resolution adapted grids for remeshed vortex methods on multicore architectures

Rossinelli

Hejazialhosseini

Rees

et al. 2015

Journal of Computational Physics

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“…Its most important advantage in the present context is that it provides a 47 direct quantitative estimate to the hydrodynamic power in self-propelled swimming. 48 Although the CFD modelling of collective swimming is not new, most of the prior work 49 has been limited to groups of two-dimensional (2D) swimmers in 2D fluids [16][17][18][19][20][21][22][23][24][25]. To test the influence of phase difference, for each position (circles) we implemented four simulations (δφ = 0, T /4, T /2 and 3T /4, respectively).…”

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confidence: 99%

On the energetics and stability of a minimal fish school

Kolomenskiy

Líu

et al. 2019

Preprint

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The physical basis for fish schooling is examined using three-dimensional numerical simulations of a pair of swimming fish, with kinematics and geometry obtained from experimental data. Energy expenditure and efficiency are evaluated using a cost of transport function, while the effect of schooling on the stability of each swimmer is examined by probing the lateral force and the lateral and longitudinal force fluctuations. We construct full maps of the aforementioned quantities as functions of the spatial pattern of the swimming fish pair and show that both energy expenditure and stability can be invoked as possible reasons for the swimming patterns and tail-beat synchronization observed in real fish. Our results suggest that high cost of transport zones should be avoided by the fish. Wake capture may be energetically unfavorable in the absence of kinematic adjustment. We hereby hypothesize that fish may restrain from wake capturing and, instead, adopt side-to-side configuration as a conservative strategy, when the conditions of wake energy harvesting are not satisfied. To maintain a stable school configuration, compromise between propulsive efficiency and stability, as well as between school members, ought to be considered. 2 result from complex social reasons [1-4]. Depending on the species, animals aggregate 3 and modulate group cohesion to improve foraging and reproductive success, avoid 4 predators or facilitate predation. Global cohesive decision and action for the whole 5 group result from different types of interaction at the local scale. Fish schools, for 6 instance, are an archetypal example of how local interactions lead to complex global 7 decisions and motions [5]. Fish interact through vision but also by sensing the 8 surrounding flow using their lateral line system [6]. From the fluid dynamics perspective, 9 hydrodynamic interactions between neighbors have often been associated with swimming 10 efficiency strategies, considering how each individual in the school is affected by the 11 vortical flows produced by its neighbors. Breder [7] already recognized the importance 12 of this issue, and more recent works have described how fish make use of vortices when 13 swimming through an unsteady flow, whether produced by neighboring fish or by other 14 March 27, 2019 1/14 features in the environment (see e.g. the review by Liao [8]). Concerning collaborative 15interactions between swimming fish, the first clear picture was proposed in the early 16 70's by Weihs' pioneering work [9]. He focused on interactions within a two-dimensional 17 layer of a three-dimensional school, and proposed an idealized two-dimensional model in 18 which each individual in the fish school places itself to benefit from the wakes generated 19 by its two nearest neighbors, giving rise to a precise diamond-like pattern. 20Weihs' theory has been followed by extensive experimental verification generally 21 comforting the idea of decreased energetic cost of locomotion in fish schools. Thus, 50We are only aware of two previous three-di...

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Reinforcement Learning and Wavelet Adapted Vortex Methods for Simulations of Self-propelled Swimmers

Cited by 107 publications

References 51 publications

Streaming-enhanced flow-mediated transport

Streaming-enhanced flow-mediated transport

MRAG-I2D: Multi-resolution adapted grids for remeshed vortex methods on multicore architectures

On the energetics and stability of a minimal fish school

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