Latest in physics.flu-dyn

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Finite-size spherical particles in a square duct flow of an elastoviscoplastic fluid: an experimental studyMay 17 2019The present experimental study addresses the flow of a Yield Stress Fluid with some elasticity (Carbopol gel) in a square duct. The behaviour of two fluids with lower and higher yield stress is investigated at multiple Reynolds numbers $Re^* \in$ (1, ... More
Angular momentum transport by the GSF instability: nonlinear simulations at the equatorMay 16 2019We present an investigation into the nonlinear evolution of the Goldreich-Schubert-Fricke (GSF) instability using axisymmetric and three-dimensional simulations near the equator of a differentially rotating radiation zone. This instability may provide ... More
Controlling secondary flow in Taylor-Couette turbulence through spanwise-varying roughnessMay 16 2019Highly turbulent Taylor-Couette flow with spanwise-varying roughness is investigated experimentally and numerically (direct numerical simulations (DNS) with an immersed boundary method (IBM)) to determine the effects of the spacing and axial width $s$ ... More
Beamed UV sonoluminescence by aspherical air bubble collapse near liquid-metal microparticlesMay 16 2019Irradiation with UV-C band ultraviolet light is one of the most commonly used ways of disinfecting water contaminated by pathogens such as bacteria and viruses. Sonoluminescence, the emission of light from acoustically-induced collapse of air bubbles ... More
A multi-prediction implicit scheme for steady state solutions of gas flow in all flow regimesMay 16 2019An implicit multiscale method with multiple macroscopic prediction for steady state solutions of gas flow in all flow regimes is presented. The method is based on the finite volume discrete velocity method (DVM) framework. At the cell interface a multiscale ... More
A multi-physics methodology for four-states of matterMay 16 2019We propose a numerical methodology for the simultaneous numerical simulation of four states of matter; gas, liquid, elastoplastic solids and plasma. The distinct, interacting physical processes are described by a combination of compressible, inert and ... More
Efficiency limits of the three-sphere swimmerMay 16 2019We consider a swimmer consisting of a collinear assembly of three spheres connected by two slender rods. This swimmer can propel itself forward by varying the lengths of the rods in a way that is not invariant under time reversal. Although any non-reciprocal ... More
Crack formation and self-closing in shrinkable, granular packingsMay 15 2019Many clays, soils, biological tissues, foods, and coatings are shrinkable, granular materials: they are composed of packed, hydrated grains that shrink when dried. In many cases, these packings crack during drying, critically hindering applications. However, ... More
Using Acoustic Perturbations to Dynamically Tune Shear Thickening in Colloidal SuspensionsMay 15 2019Colloidal suspensions in industrial processes often exhibit shear thickening that is difficult to control actively. Here, we use piezoelectric transducers to apply acoustic perturbations to dynamically tune the suspension viscosity in the shear-thickening ... More
Sinusoidal-gust generation with a pitching and plunging airfoilMay 15 2019The generation of uniform, periodic gust disturbances in an experimental context is demonstrated using a single oscillating airfoil. A pitching and heaving symmetric airfoil is suggested as a simpler alternative to existing gust-generation methods. The ... More
Condensate formation and multiscale dynamics in two-dimensional active suspensionsMay 15 2019The collective effects of microswimmers in active suspensions result in active turbulence, a spatiotemporally chaotic dynamics at mesoscale, which is characterized by the presence of vortices and jets at scales much larger than the characteristic size ... More
On-demand contact line pinning during droplet evaporationMay 15 2019Depending on the contact line motion, colloid-rich drolets evaporation can leave a ring-like or a spot-like residue. Herein, we determine this outcome by controlling the contact line motion using coplanar direct current electrowetting-on-dielectrics (DC-EWOD). ... More
Higher-order realizable turbulence modeling based on the square root tensor of the Reynolds stressMay 15 2019In this study, realizable turbulence modeling based on the square root tensor of the Reynolds stress [Phys. Rev. E \textbf{92}, 053010 (2015)] is further developed for extending its applicability to more complex flows. In conventional methods, it was ... More
Approaching Earth's core conditions in high-resolution geodynamo simulationsMay 15 2019The geodynamo features a broad separation between the large scale at which Earth's magnetic field is sustained against ohmic dissipation and the small scales of the turbulent and electrically conducting underlying fluid flow in the outer core. Here, the ... More
On the multi-symplectic structure of Boussinesq-type systems. II: Geometric discretizationMay 15 2019In this paper we consider the numerical approximation of systems of Boussinesq-type to model surface wave propagation. Some theoretical properties of these systems (multi-symplectic and Hamiltonian formulations, well-posedness and existence of solitary-wave ... More
Synchronization to big-data: nudging the Navier-Stokes equations for data assimilation of turbulent flowsMay 14 2019Nudging is an important data assimilation technique where partial field measurements are used to control the evolution of a dynamical system and/or to reconstruct the entire phase-space configuration of the supplied flow. Here, we apply it to the toughest ... More
Faraday instability on a sphere: Floquet analysisMay 14 2019Standing waves appear at the surface of a spherical viscous liquid drop subjected to radial parametric oscillation. This is the spherical analogue of the Faraday instability. Modifying the Kumar & Tuckerman (1994) planar solution to a spherical interface, ... More
Meso-resolved simulations of shock-to-detonation transition in nitromethane with air-filled cavitiesMay 14 2019Two-dimensional, meso-resolved numerical simulations are performed to investigate the complete shock-to-detonation transition (SDT) process in a mixture of liquid nitromethane (NM) and air-filled, circular cavities. The shock-induced initiation behaviors ... More
Meso-resolved simulations of shock-to-detonation transition in nitromethane with air-filled cavitiesMay 14 2019May 15 2019Two-dimensional, meso-resolved numerical simulations are performed to investigate the complete shock-to-detonation transition (SDT) process in a mixture of liquid nitromethane (NM) and air-filled, circular cavities. The shock-induced initiation behaviors ... More
Numerical Study of Laminar and Turbulent Natural Convection from a Stack of Solid Horizontal CylindersMay 14 2019Natural convection from a stack of isothermal solid horizontal cylinders has been investigated numerically in a three dimensional computational domain. Simulations were conducted in both laminar and turbulent flow regimes of Rayleigh number (Ra) spanning ... More
Rayleigh-Benard convection in a nonuniformly rotating electrically conductive medium in an external spiral magnetic fieldMay 14 2019The research is devoted to the stability of convective flow in a nonuniformly rotating layer of an electrically conducting fluid in a spiral magnetic field. The stationary and oscillatory modes of magnetic convection are considered depending on the profile ... More
Fluid Structure Interaction modelling using Lattice Boltzmann and Volume Penalization methodMay 13 2019This paper proposes an approach combining the Volume Penalization (VP) and the the Lattice Boltzmann method (LBM) to compute fluid structure interaction involving rigid bodies. The method consists in adding a force term in the LBM formulation, and thus ... More
Dynamics of individual Brownian rods in a microchannel flowMay 13 2019We study the orientational dynamics of heavy silica microrods flowing through a microfluidic channel. Comparing experiments and Brownian dynamics simulations we identify different particle orbits, in particular in-plane tumbling behavior, which cannot ... More
A non-empirical free volume viscosity model for alkane lubricants under severe pressuresMay 13 2019Viscosities $\eta$ and diffusion coefficients $D_s$ of linear and branched alkanes at high pressures $P$$<$0.7 GPa and temperatures $T$=500-600 K are calculated by equilibrium molecular dynamics. Combining Stokes-Einstein, free volume and random walk ... More
Superharmonic instability of nonlinear traveling wave solutions in Hamiltonian systemsMay 13 2019The problem of linear instability of a nonlinear traveling wave in a canonical Hamiltonian system with translational symmetry subject to superharmonic perturbations is discussed. It is shown that exchange of stability occurs when energy is stationary ... More
Swirling fluid flow in flexible, expandable elastic tubes: variational approach, reductions and integrabilityMay 11 2019Many engineering and physiological applications deal with situations when a fluid is moving in flexible tubes with elastic walls. In the real-life applications like blood flow, there is often an additional complexity of vorticity being present in the ... More
Wellposedness of the discontinuous ODE associated with two-phase flowsMay 11 2019We consider the initial value problem \[ \dot x (t) = v(t,x(t)) \;\mbox{ for } t\in (a,b), \;\; x(t_0)=x_0 \] which determines the pathlines of a two-phase flow, i.e.\ $v=v(t,x)$ is a given velocity field of the type \[ v(t,x)= \begin{cases} v^+(t,x) ... More
Faraday instability on a sphere: numerical simulationMay 11 2019We consider a spherical variant of the Faraday problem, in which a spherical drop is subjected to a time-periodic body force, as well as surface tension. We use a full three-dimensional parallel front-tracking code to calculate the interface motion of ... More
Wind-sustained viscous solitonsMay 11 2019When wind blows at the surface of a liquid of sufficiently high viscosity, a wave packet of small amplitude is first generated, which sporadically forms large-amplitude fluid bumps that rapidly propagate downstream. These nonlinear structures, first observed ... More
Wave propagation in stenotic vessels; theoretical analysis and comparison between 3D and 1D fluid-structure-interaction modelsMay 10 2019Using analytical expressions for the pressure and velocity waveforms in tapered vessels, we construct a linear 1D model for wave propagation in stenotic vessels in the frequency domain. We demonstrate that using only two parameters to approximate the ... More
Sedimentation of a suspension of paramagnetic particles in an external magnetic fieldMay 10 2019We investigate the sedimentation of initially packed paramagnetic particles in presence of a homogeneous external magnetic field, in a Hele-Shaw cell filled with water. Although the magnetic susceptibility of the particles is small and the particle-particle ... More
Kelvin-Helmholtz billows above Richardson number $1/4$May 10 2019We study the dynamical system of a forced stratified mixing layer at finite Reynolds number $Re$, and Prandtl number $Pr=1$. We consider a hyperbolic tangent background velocity profile in the two cases of hyperbolic tangent and uniform background buoyancy ... More
Volume penalization for inhomogeneous Neumann boundary conditions modeling scalar flux in complicated geometryMay 09 2019We develop a volume penalization method for inhomogeneous Neumann boundary conditions, generalizing the flux-based volume penalization method for homogeneous Neumann boundary condition proposed by Kadoch et al. [J. Comput. Phys. 231 (2012) 4365]. The ... More
Almost-sure exponential mixing of passive scalars by the stochastic Navier-Stokes equationsMay 09 2019We deduce almost-sure exponentially fast mixing of passive scalars advected by solutions of the stochastically-forced 2D Navier-Stokes equations and 3D hyper-viscous Navier-Stokes equations in $\mathbb T^d$ subjected to non-denegenerate $H^\sigma$-regular ... More
Self-similar analysis of a viscous heated Oberbeck-Boussinesq flow systemMay 09 2019The simplest model to couple the heat conduction and Navier-Stokes equations together is the Oberbeck-Boussinesq(OB)system which were investigated by E.N. Lorenz and opened the paradigm of chaos. In our former studies - Chaos, Solitons and Fractals 78, ... More
Baropycnal Work: A Mechanism for Energy Transfer Across ScalesMay 09 2019The role of baroclinicity, which arises from the misalignment of pressure and density gradients, is well-known in the vorticity equation, yet its role in the kinetic energy budget has never been obvious. Here, we show that baroclinicity appears naturally ... More
A Computational Model for Bacterial Run-and-Tumble MotionMay 08 2019In our article we present a computational model for the simulation of self-propelled anisotropic bacteria. To this end we use a self-propelled particle model and augment it with a statistical algorithm for the run-and-tumble motion. We derive an equation ... More
Sufficient conditions for dual cascade flux laws in the stochastic 2d Navier-Stokes equationsMay 08 2019We provide sufficient conditions for mathematically rigorous proofs of the third order universal laws capturing the energy flux to large scales and enstrophy flux to small scales for statistically stationary, forced-dissipated 2d Navier-Stokes equations ... More
The flow field around a confined active dropletMay 08 2019We present here first-of-a-kind experimental measurements of the flow field around a swimming water droplet, using confocal PIV in three dimensions. The droplet is denser than the continuous oil phase, and swims close and parallel to the bottom wall. ... More
Letter: Modified normalized Rortex/vortex identification methodMay 08 2019In this paper, a modified normalized Rortex/vortex identification method named Omega_R is presented to improve the original Omega_R method and cure the bulging phenomenon on the iso-surfaces caused by the original Omega_R method. Detailed mathematical ... More
Letter: Mathematical Foundation of Turbulence Generation-Symmetric to Asymmetric Liutex/RortexMay 08 2019Vortex has been considered as the building block and muscle of turbulence for long time. A new physical quantity called Liutex (previously named Rortex) has been defined as the rigid rotation part of fluid motion. From DNS and experiment, forest of hairpin ... More
Dimensional analysis of two-dimensional turbulenceMay 08 2019We study the scaling properties of two-dimensional turbulence using dimensional analysis. In particular, we consider the energy spectrum both at large and small scales and in the "inertial ranges" for the cases of freely decaying and forced turbulence. ... More
The kinetic exclusion process: A tale of two fieldsMay 08 2019We introduce a general class of stochastic lattice gas models, and derive their fluctuating hydrodynamics description in the large size limit under a local equilibrium hypothesis. The model consists in energetic particles on a lattice subject to exclusion ... More
A note on forces exerted by a Stokeslet on confining boundariesMay 08 2019We consider a Stokeslet applied to a viscous fluid next to an infinite, flat wall, or in-between two parallel walls. We calculate the forces exerted by the resulting flow on the confining boundaries, and use the results obtained to estimate the hydrodynamic ... More
Three dimensional high-order gas-kinetic scheme for supersonic isotropic turbulence I: criterion for direct numerical simulationMay 08 2019In this paper, we intend to address the high-order gas-kinetic scheme (HGKS) in the direct numerical simulation (DNS) of compressible isotropic turbulence up to the supersonic regime. With the consideration of robustness and accuracy, the WENO-Z scheme ... More
Modern theory of hydraulic fracture modeling with using explicit and implicit schemesMay 08 2019The paper presents novel results, obtained on the basis of the modified theory of hydraulic fractures (HF). The theory underlines significance of the speed equation. When applied to numerical simulation of HF, the theory reveals three distinct issues: ... More
Comparisons of Two Reduced-Order Models for Linearized Unsteady Aerodynamic IdentificationMay 08 2019This paper compares the performance of two unsteady aerodynamic reduced-order models (ROMs), namely linear Volterra series and the autoregressive with exogenous input (ARX) model, on modeling dynamically linear aerodynamic behaviors. The difference between ... More
Refractive index matching (RIM) using double-binary liquid-liquid mixturesMay 07 2019Within the last decade microscopic multiphase flows have gained broad interest. An exact understanding of the underlying hydrodynamic interrelations is the key for successful reactor layout and reaction control. To examine the local hydrodynamic behavior, ... More
Modeling the excess velocity of low-viscous Taylor droplets in square microchannelsMay 07 2019Microscopic multiphase flows have gained broad interest due to their capability to transfer processes into new operational windows and achieving significant process intensification. However, the hydrodynamic behavior of Taylor droplets is not yet entirely ... More
Dynamic wake modulation induced by utility-scale wind turbine operationMay 07 2019Understanding wind turbine wake mixing and recovery is critical for improving the power generation and structural stability of downwind turbines in a wind farm. In the field, where incoming flow and turbine operation are constantly changing, wake recovery ... More
Maximum Entropy Method for Solving the Turbulent Channel Flow ProblemMay 07 2019There are two components in this work that allow solutions of the turbulent channel problem: one is the Galilean-transformed Navier-Stokes equation which gives a theoretical expression for the Reynolds stress; and the second the maximum entropy principle ... More
Predictions of turbulent shear flows using deep neural networksMay 07 2019In the present work we assess the capabilities of neural networks to predict temporally evolving turbulent flows. In particular, we use the nine-equation shear flow model by Moehlis et al. [New J. Phys. 6, 56 (2004)] to generate training data for two ... More
Lagrangian statistics of pressure fluctuation events in homogeneous isotropic turbulenceMay 07 2019Homogeneous and isotropic turbulent fields obtained from two DNS databases (with $\Re_\lambda$ equal to 150 and 418) were seeded with point particles that moved with the local fluid velocity to obtain Lagrangian pressure histories. Motivated by cavitation ... More
Decomposition of the forces on a body moving in an incompressible fluidMay 07 2019The identification of separate physical features contributing to the force resultants on a moving body is useful for insight into the associated flow, and for conceptual modelling. A natural approach is to seek a component due to viscosity and an `inviscid' ... More
Collinear velocity relaxation of two spheres in a viscous incompressible fluidMay 07 2019Collinear velocity relaxation of two spheres immersed in a viscous incompressible fluid is studied on the basis of an approximate expression for the retarded hydrodynamic interaction. After a sudden impulse applied to one sphere, the other one instantaneously ... More
Probability of noise-induced separatrix crossing for inertial particles in flowsMay 07 2019The motion of weakly inertial Brownian particles, transported by steady two-dimensional fluid flows, is investigated by means of asymptotic methods. We focus on the phenomenon of noise-induced separatrix crossing, which can force particles to enter or ... More
Turbulent lithosphere deformation in the Tibetan PlateauMay 07 2019In this work, we show that the Tibetan Plateau deformation demonstrates a turbulence-like statistics, e.g., spatial invariance cross continuous scales. A dual-power-law behavior is evident to show the existence of two possible conversation laws for the ... More
Direction splitting scheme for Navier-Stokes-Boussinesq system in spherical shell geometriesMay 07 2019This paper introduces a second-order direction-splitting method for solving the incompressible Navier-Stokes-Boussinesq system in a spherical shell region. The equations are solved on overset Yin-Yang grids, combined with spherical coordinate transforms. ... More
The motion of buoyant point vorticesMay 06 2019A general formulation is presented for studying the motion of buoyant vortices. It extends the well-known Hamiltonian framework for interacting homogeneous point vortices to include buoyancy effects acting on the vortices. This is then used to systematically ... More
Stochastic Closures for Wave--Current Interaction DynamicsMay 06 2019May 13 2019We apply the well-known generalized Lagrangian mean (GLM) theory and classical WKB wave dispersion theory in combination with recent developments in stochastic geometric fluid mechanics to derive a framework for estimating uncertainty for wave--current ... More
A Stochastic Closure for Wave--Current Interaction DynamicsMay 06 2019We apply the well-known generalised Lagrangian mean (GLM) theory and classical wave dispersion theory in combination with recent developments in stochastic geometric fluid mechanics to provide a framework for estimating uncertainty in wave--current interaction ... More
Stochastic Closures for Wave--Current Interaction DynamicsMay 06 2019May 14 2019We apply the well-known generalized Lagrangian mean (GLM) theory and classical WKB wave dispersion theory in combination with recent developments in stochastic geometric fluid mechanics to derive a framework for estimating uncertainty for wave--current ... More
Formation and decay of eddy currents generated by crossed surface wavesMay 06 2019The mass-transport induced by crossed surface waves consists of the Stokes and Euler contributions which are very different in nature. The first contribution is a generalization of Stokes drift for a plane wave in ideal fluid and the second contribution ... More
Spirals and ribbons in counter-rotating Taylor-Couette flow: frequencies from mean flows and heteroclinic orbitsMay 05 2019A number of time-periodic flows have been found to have a property called RZIF: when a linear stability analysis is carried out about the temporal mean (rather than the usual steady state), an eigenvalue is obtained whose Real part is Zero and whose Imaginary ... More
Path-following methods for calculating linear surface wave dispersion relations on vertical shear flowsMay 05 2019The path-following scheme in [Loisel and Maxwell, SIAM J. Matrix Anal. Appl., 39-4 (2018), pp. 1726-1749] is adapted to efficiently calculate the dispersion relation curve for linear surface waves on an arbitrary vertical shear current. This is equivalent ... More
The Statistical Properties of Superfluid Turbulence in $^4$He from the Hall-Vinen-Bekharevich-Khalatnikov ModelMay 04 2019We obtain the von K\'arm\'an-Howarth relation for the stochastically forced three-dimensional Hall-Vinen-Bekharvich-Khalatnikov (3D HVBK) model of superfluid turbulence in Helium ($^4$He) by using the generating-functional approach. We combine direct ... More
The RWST, a comprehensive statistical description of the non-Gaussian structures in the ISMMay 03 2019The interstellar medium (ISM) is a complex non-linear system governed by gravity and magneto-hydrodynamics, as well as radiative, thermodynamical, and chemical processes. Our understanding of it mostly progresses through observations and numerical simulations, ... More
Large-scale magnetic dynamos in non-helical and helical flows and a generalized quenching formalismMay 03 2019For ideal MHD, we analytically show that both helical and non-helical anisotropic velocity flows which dynamo amplify large-scale magnetic fields, also grow large-scale magnetic helicity. We then derive a new generalized quenching formalism for these ... More
Numerical study of the behaviors of ventilated supercavities in a periodic gust flowMay 02 2019We conducted a numerical simulation of ventilated supercavitation from a forward-facing cavitator in unsteady flows generated by a gust generator under different gust angles of attack and gust frequencies. The numerical method is validated through the ... More
The Probability Distribution of Density Fluctuations in Supersonic TurbulenceMay 02 2019We study density fluctuations in supersonic turbulence using both theoretical methods and numerical simulations. A theoretical formulation is developed for the probability distribution function (PDF) of the density at steady state, connecting it to the ... More
Fluid-structure coupling of concentric double FGM shells with different lengthsMay 02 2019The aim of this study is to develop a semi-analytical method to investigate fluid-structure coupling of concentric double shells with different lengths and elastic behaviours. Co-axial shells constitute a cylindrical circular container and a baffle submerged ... More
Gravitational waves from first-order phase transitions: Ultra-supercooled transitions and the fate of relativistic shocksMay 02 2019We study the gravitational wave (GW) production in extremely strong first order phase transitions where the latent heat density dominates the plasma energy density, $\alpha \gtrsim 1$. In such transitions, bubbles develop extremely thin and relativistic ... More
Modeling tissue perfusion in terms of 1d-3d embedded mixed-dimension coupled problems with distributed sourcesMay 02 2019We present a new method for modeling tissue perfusion on the capillary scale. The microvasculature is represented by a network of one-dimensional vessel segments embedded in the extra-vascular space. Vascular and extra-vascular space exchange fluid over ... More
Collective Dynamics in a Monolayer of Squirmers Confined to a Boundary by GravityMay 01 2019We present a hydrodynamic study of a monolayer of squirmer model microswimmers confined to a boundary by strong gravity using the simulation method of multi-particle collision dynamics. The squirmers interact with each other via their self-generated hydrodynamic ... More
The inertial wave activity during spin-down in a rapidly penny shaped cylinder. Part II The inertial wave of maximum frequency triggerMay 01 2019In an earlier paper, Oruba, Soward & Dormy (J.Fluid Mech., vol.818, 2017, pp.205-240) considered the primary quasi-steady geostrophic (QG) motion of a constant density fluid of viscosity $\nu$ that occurs during linear spin-down in a cylindrical container ... More
The inertial wave activity during spin-down in a rapidly rotating penny shaped cylinder. Part I The quasi-geostrophic triggerMay 01 2019In a previous paper, Oruba, Soward & Dormy (J.Fluid Mech., vol.818, 2017, pp.205-240) considered the primary quasi-steady geostrophic (QG) motion of a constant density fluid of viscosity $\nu$ that occurs during linear spin-down in a cylindrical container ... More
Analogue Black Hole Spectroscopy; or, how to listen to dumb holesMay 01 2019Spectroscopy is a fundamental tool in science which consists in studying the response of a system as a function of frequency. Among its many applications in Physics, Biology, Chemistry and other fields, the possibility of identifying objects and structures ... More
Dynamics of the critical Casimir force for a conserved order parameter after a critical quenchMay 01 2019Fluctuation-induced forces occur generically when long-ranged correlations (e.g., in fluids) are confined by external bodies. In classical systems, such correlations require specific conditions, e.g., a medium close to a critical point. On the other hand, ... More
Scaling mean velocity in two-dimensional turbulent wall jetsMay 01 2019Scaling approaches for mean velocity in two-dimensional, fully-developed, turbulent wall jets developing on flat surfaces, have invariably reckoned on the nozzle initial conditions as scaling parameters. This choice, however, does not square with the ... More
An immersed boundary method for fluid--structure--acoustics interactions involving large deformations and complex geometriesMay 01 2019This paper presents an immersed boundary (IB) method for fluid--structure--acoustics interactions involving large deformations and complex geometries. In this method, the fluid dynamics is solved by a finite difference method where the temporal, viscous ... More
Model-Based Estimation of Vortex Shedding in Unsteady Cylinder WakesApr 30 2019This paper considers single-sensor estimation of vortex shedding in cylinder wakes at $Re=100$ in simulations and at $Re=1036$ in experiments. A model based on harmonic decomposition is developed to capture the periodic dynamics of vortex shedding. Two ... More
Eelectrokinetic turbulence and chaos in ionic migration and in microfluidic convectionApr 30 2019Turbulence in the ionic migration and in the microfluidic electro-hydrodynamic convection (mixing) under constant and low-frequency external electric field has been studied using distributed chaos approach and notion of effective (turbulent) diffusivity. ... More
A critical point for bifurcation cascades and featureless turbulenceApr 30 2019In this Letter we show that a bifurcation cascade and fully sustained turbulence can share the phase space of a fluid flow system, resulting in the presence of competing stable attractors. We analyse the toroidal pipe flow, which undergoes subcritical ... More
A critical point for bifurcation cascades and featureless turbulenceApr 30 2019May 02 2019In this Letter we show that a bifurcation cascade and fully sustained turbulence can share the phase space of a fluid flow system, resulting in the presence of competing stable attractors. We analyse the toroidal pipe flow, which undergoes subcritical ... More
On the convergence of the normal form transformation in discrete Rossby and drift wave turbulenceApr 30 2019We study numerically the region of convergence of the normal form transformation for the case of the Charney-Hasagawa-Mima (CHM) equation to investigate whether certain finite amplitude effects can be described in normal coordinates. We do this by taking ... More
4D-Flow MRI Pressure Estimation Using Velocity Measurement-Error based Weighted Least-SquaresApr 30 2019This work introduces a 4D-flow magnetic resonance imaging (MRI) pressure reconstruction method which employs weighted least-squares (WLS) for pressure integration. Pressure gradients are calculated from the velocity fields, and velocity errors are estimated ... More
An asymptotic preserving well-balanced scheme for the isothermal fluid equations in low-temperature plasma applicationsApr 30 2019We present a novel numerical scheme for the efficient and accurate solution of the isothermal two-fluid (electron and ion) equations coupled to Poisson's equation for low-temperature plasmas. The model considers electrons and ions as separate fluids, ... More
Lattices of hydrodynamically interacting flapping swimmersApr 30 2019Fish schools and bird flocks exhibit complex collective dynamics whose self-organization principles are largely unknown. The influence of hydrodynamics on such collectives has been relatively unexplored theoretically, in part due to the difficulty in ... More
Landmarks and Frontiers in Biological Fluid DynamicsApr 30 2019Biological systems are influenced by fluid mechanics at nearly all spatiotemporal scales. This broad relevance of fluid mechanics to biology has been increasingly appreciated by engineers and biologists alike, leading to continued expansion of research ... More
Solitary wave fission of a large disturbance in a viscous fluid conduitApr 29 2019The temporal evolution of a large, localized initial disturbance is considered in the context of the viscous fluid conduit system---the driven, cylindrical, free interface between two miscible Stokes fluids with high viscosity contrast. Due to buoyancy ... More
Fluctuations of separation of trajectories in chaos and correlation dimensionApr 29 2019We study the generalized Lyapunov exponent that gives the logarithmic growth exponents of the moments of the distance between two infinitesimally close trajectories of a chaotic system. The Legendre transform of the exponent is a large deviations function. ... More
Spontaneous Transport Barriers Quench Turbulent Resistivity in 2D MHDApr 29 2019This Letter identifies the physical mechanism for the quench of turbulent resistivity in 2D MHD. Without an imposed, ordered magnetic field, a multi-scale, blob-and-barrier structure of magnetic potential forms spontaneously. Magnetic energy is concentrated ... More
CHNS: A case study of turbulence in elastic mediaApr 29 2019Recent progress in the study of Cahn-Hilliard Navier-Stokes (CHNS) turbulence is summarized. This is an example of \textit{elastic turbulence}, which can occur in elastic (i.e. self-restoring) media. Such media exhibit memory due freezing-in laws, as ... More
Streak formation in flow over Biomimetic Fish Scale ArraysApr 29 2019May 03 2019The surface topology of the scale pattern from the European Sea Bass (Dicentrarchus labrax ) was measured using a digital microscope and geometrically reconstructed using Computer Assisted Design modelling. Numerical flow simulations and experiments with ... More
Streak formation in flow over Biomimetic Fish Scale ArraysApr 29 2019The surface topology of the scale pattern from the European Sea Bass (Dicentrarchus labrax ) was measured using a digital microscope and geometrically reconstructed using Computer Assisted Design modelling. Numerical flow simulations and experiments with ... More
A nonlinear subgrid-scale model for large-eddy simulations of rotating turbulent flowsApr 29 2019Rotating turbulent flows form a challenging test case for large-eddy simulation (LES). We, therefore, propose and validate a new subgrid-scale (SGS) model for such flows. The proposed SGS model consists of a dissipative eddy viscosity term as well as ... More
High-order DG solvers for under-resolved turbulent incompressible flows: A comparison of $L^2$ and $H$(div) methodsApr 29 2019The accurate numerical simulation of turbulent incompressible flows is a challenging topic in computational fluid dynamics. For discretisation methods to be robust in the under-resolved regime, mass conservation as well as energy stability are key ingredients ... More
Thermal Dendrites on the Surface of Water and Water SolutionApr 29 2019Thermal dendrites (fractal-like structures) on the surface of water and some water solutions are found with an infrared camera. They are observed with specific sizes and temperature differences in the liquid and are not associated with the movement of ... More
Universality in coalescence of polymeric fluid dropsApr 28 2019We unveil universal temporal evolution of the necking radius during the coalescence of polymeric drops. Through high speed imaging we have demonstrated that drops of polyacrylamide (PAM), poly-vinyl alcohol (PVA), polyethylene oxide (PEO), polyethylene ... More
Experimental and numerical investigation of the hydrodynamic characteristics of Autonomous Underwater Vehicles over sea-beds with complex topographyApr 28 2019Improved designs for Autonomous Underwater Vehicles (AUV) are becoming increasingly important due to their utility in academic and industrial applications. However, a majority of such testing and design is carried out under conditions that may not reflect ... More