Controlling turbulent drag across electrolytes using electric fields

Ostilla–Mónico, Rodolfo; Lee, Alpha A.

doi:10.1039/c6fd00247a

Cited by 7 publications

(23 citation statements)

References 39 publications

(44 reference statements)

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“…Former is in quantitative agreement with available direct numerical simulations (DNS) that predict Re ref τ = 170 (e.g. [3]). HD ODT simulation results (cyan lines in figure 2) exhibit good agreement with DNS [3] and the empirical law of the wall for the von-Kármán constant κ 0.39 and additive constant B 4.2 [8].…”

Section: Model Formulation and Application To Ehd Couette Flowsupporting

confidence: 87%

“…[3]). HD ODT simulation results (cyan lines in figure 2) exhibit good agreement with DNS [3] and the empirical law of the wall for the von-Kármán constant κ 0.39 and additive constant B 4.2 [8]. ODT captures the viscous sublayer (y + 10) and the logarithmic layer (y + 80), but it does not capture the relative 'overshoot' in the buffer layer (across 10 y + 80), which is a similar as in turbulent Poiseuille flow [9].…”

Section: Model Formulation and Application To Ehd Couette Flowmentioning

confidence: 99%

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Towards a stochastic model for electrohydrodynamic turbulence with application to electrolytes

Klein

Schmidt

2021

Proc Appl Math and Mech

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We investigate turbulent Couette flows of dilute, weakly-conducting electrolytes by utilizing the stochastic one-dimensional turbulence (ODT) model. The flow is driven by relative motion of the top and bottom wall and affected by an electric field between these walls that is prescribed by a voltage difference. The electrolytes considered have zero bulk charge and consist of two ion species with the same mobility, valence, and initial concentration. The stochastic model predicts a decrease of the mean streamwise velocity when an external voltage is applied provided that both Schmidt (Sc) and Reynolds (Re) numbers are sufficiently large, that is, Sc 30 for Re = 12000 investigated. The effect observed is relevant for flow control, but the mechanism awaits clarification. Present ODT results may help to develop this understanding or design laboratory experiments.

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Section: Model Formulation and Application To Ehd Couette Flowsupporting

confidence: 87%

Section: Model Formulation and Application To Ehd Couette Flowmentioning

confidence: 99%

Towards a stochastic model for electrohydrodynamic turbulence with application to electrolytes

Klein

Schmidt

2021

Proc Appl Math and Mech

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“…We consider constant-property EHD flows of weakly conducting fluids that are described by the Navier-Stokes equations coupled to the Poisson-Nernst-Planck equations and an equation for the electric potential (see, for example, [6]). The simplest EHD flows are only one-way coupled, that is, the electric field is prescribed so that eletrokinetics evolve independently of the flow when electric charges are highly diluted.…”

Section: Odt Governing Equations For Momentum Conservation In Ehd Flowsmentioning

confidence: 99%

“…In a first category, EHD effects are subordinated to the flow dynamics and do not play a relevant role, except for the enhancement of specific properties of an application, as in EHD-enhanced heat exchangers [1,2] or plasma-assisted flames [3]. In a second category, EHD effects determine the nature of the application and, thus, have leading order effects on the flow, as in the case of industrial electrostatic precipitation [4,5] or flow control [6]. The electrokinetics and the flow are affected by transient processes on all relevant scales, such that robust, accurate, but also economical modeling strategies, are required to tackle these flows.…”

Section: Introductionmentioning

confidence: 99%

EHD Turbulence in Channel Flows with Inhomogeneous Electrical Fields: A One-Dimensional Turbulence Study

Schmidt¹,

Méndez²,

Klein³

2021

14th WCCM-ECCOMAS Congress

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Electricly enhanced flows can be found in various technical applications as, for example, in air cleaning devices and liquid metal or redox flow batteries. For both examples mentioned it is crucial to develop a general understanding of the relevant physical processes and model them economically. Additionally, a correct upscaling procedure is specifically relevant for the transition into the industrial scale. All of these aspects are challenging because of the multiscale and multiphysics nature of these flows. In this paper we present a lower-order modeling strategy that aims to bridge the gap between fundamental research and applications by utilizing stochastic one-dimensional turbulence (ODT). Two case studies are performed. One is for two-way coupled turbulent Couette flow of electrolytes and another for one-way coupled planar Poiseuille flow in a wire-plate electrostatic precipitator. By comparison with reference data, we show that the modeling approach is robust and has predictive capabilities. Nevertheless, we also discuss some limitations of the purely one-dimensional and stochastic dynamical representation.

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“…For simplicity we have dropped the weak dependence of permittivity on the electric fields [57] which for most purposes are insignificant [12]. Now, using (32) and (22) we can write…”

Section: Derivation Of the Modelmentioning

confidence: 99%

Transient electrohydrodynamic flow with concentration-dependent fluid properties: Modelling and energy-stable numerical schemes

Linga

Bolet

Mathiesen

2020

Journal of Computational Physics

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Transport of electrolytic solutions under influence of electric fields occurs in phenomena ranging from biology to geophysics. Here, we present a continuum model for single-phase electrohydrodynamic flow, which can be derived from fundamental thermodynamic principles. This results in a generalized Navier-Stokes-Poisson-Nernst-Planck system, where fluid properties such as density and permittivity depend on the ion concentration fields. We propose strategies for constructing numerical schemes for this set of equations, where the electrochemical and the hydrodynamic subproblems are decoupled at each time step. We provide time discretizations of the model that suffice to satisfy the same energy dissipation law as the continuous model. In particular, we propose both linear and non-linear discretizations of the electrochemical subproblem, along with a projection scheme for the fluid flow. The efficiency of the approach is demonstrated by numerical simulations using several of the proposed schemes.have often aimed for the steady-state solution to the governing equations [15,24]. To this end, commercial multi-physics software packages (e.g. Comsol) are available, and have long been successfully applied to simulate a variety microfluidic systems. With regard to the transient development of streaming potential, detailed simulations have often been limited to two-dimensional or axisymmetric geometries such as finitelength symmetric channels [25,26]. In studies of electroconvection near permselective membranes [27], both finite element [28] and (pseudo-) spectral methods [29][30][31] have proven efficient. Recently, a spectral method was also applied in a study of the interaction between electrokinetics and turbulent drag [32]. In simulations of electrokinetic flow, the electrolyte solutions are usually assumed to be dilute enough for density, viscosity and permittivity to be independent of the local ion concentrations. The ion mobilities are usually taken to be proportional to the concentrations.For the separate subproblems comprising the NSPNP problem, there exists many efficient numerical methods. For the Poisson-Nernst-Planck (PNP) problem, efficient approaches have been demonstrated for semi-conductors [33] and biological ion channels [34], where e.g. dispersion and size effects of ions can be included. For transient simulation of the Navier-Stokes equations, projection methods that date back to Chorin [35,36] (see also Guermond, Minev, and Shen [37]), have imparted speedup compared to solving the monolithic problem, since it effectively decouples the computation of velocity and pressure (although at the cost of some reduced accuracy). For the full NSPNP problem, however, less is certain, but it seems clear that succesful numerical schemes should aim to decouple, at least, the fluid mechanical subproblem from the electrochemical subproblem, and thus take advantage of the progress made in numerically resolving each of these, although a direct combination does not necessarily yield a successful scheme.In the field of diff...

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Controlling turbulent drag across electrolytes using electric fields

Cited by 7 publications

References 39 publications

Towards a stochastic model for electrohydrodynamic turbulence with application to electrolytes

Towards a stochastic model for electrohydrodynamic turbulence with application to electrolytes

EHD Turbulence in Channel Flows with Inhomogeneous Electrical Fields: A One-Dimensional Turbulence Study

Transient electrohydrodynamic flow with concentration-dependent fluid properties: Modelling and energy-stable numerical schemes

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