Numerical Study of Electro-Osmotic Fluid Flow and Vortex Formation

Bezerra, Wesley De Souza; Castelo, A.; Afonso, A.M.

doi:10.3390/mi10120796

“…6 and 7 . The velocity profiles in a 2D micro-geometry (micro-channel/nozzle) has been investigated in terms of the Debye length, , Deborah number, De , cone angle, and rheological constraints by several numerical studies, such as Bezerra et al 58 , Chen et al 45 , Mei et al 44 , and Tseng et al 47 as well as analytical studies e.g. Afonso et al 52 , 57 and Wang et al 43 .…”

Section: Resultsmentioning

confidence: 99%

Ion transport and current rectification in a charged conical nanopore filled with viscoelastic fluids

Trivedi

¹

,

Nirmalkar

²

2022

Sci Rep

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The ionic current rectification (ICR) is a non-linear current-voltage response upon switching the polarity of the potential across nanopore which is similar to the I–V response in the semiconductor diode. The ICR phenomenon finds several potential applications in micro/nano-fluidics (e.g., Bio-sensors and Lab-on-Chip applications). From a biological application viewpoint, most biological fluids (e.g., blood, saliva, mucus, etc.) exhibit non-Newtonian visco-elastic behavior; their rheological properties differ from Newtonian fluids. Therefore, the resultant flow-field should show an additional dependence on the rheological material properties of viscoelastic fluids such as fluid relaxation time $$(\lambda )$$ ( λ ) and fluid extensibility $$(\varepsilon )$$ ( ε ) . Despite numerous potential applications, the comprehensive investigation of the viscoelastic behavior of the fluid on ionic concentration profile and ICR phenomena has not been attempted. ICR phenomena occur when the length scale and Debye layer thickness approaches to the same order. Therefore, this work extensively investigates the effect of visco-elasticity on the flow and ionic mass transfer along with the ICR phenomena in a single conical nanopore. The Poisson–Nernst–Planck (P–N–P) model coupled with momentum equations have been solved for a wide range of conditions such as, Deborah number, $$1\le De \le 100$$ 1 ≤ D e ≤ 100 , Debye length parameter, $$1\le \kappa R_t \le 50$$ 1 ≤ κ R t ≤ 50 , fluid extensibility parameter, $$0.05\le \varepsilon \le 0.25$$ 0.05 ≤ ε ≤ 0.25 , applied electric potential, $$-40\le V \le 40$$ - 40 ≤ V ≤ 40 , and surface charge density $$\sigma = -10$$ σ = - 10 and $$-50$$ - 50 . Limited results for Newtonian fluid ($$De = 0$$ D e = 0 , and $$\varepsilon = 0$$ ε = 0 ) have also been shown in order to demonstrate the effectiveness of non-Newtonian fluid behaviour over the Newtonian fluid behaviour. Four distinct novel characteristics of electro-osmotic flow (EOF) in a conical nanopore have been investigated here, namely (1) detailed structure of flow field and velocity distribution in viscoelastic fluids (2) influence of Deborah number and fluid extensibility parameter on ionic current rectification (ICR) (3) volumetric flow rate calculation as a function of Deborah number and fluid extensibility parameter (4) effect of viscoelastic parameters on concentration distribution of ions in the nanopore. At high applied voltage, both the extensibility parameter and Deborah number facilitate the ICR phenomena. In addition, the ICR phenomena are observed to be more pronounced at low values of $$\kappa R_t$$ κ R t than the high values of $$\kappa R_t$$ κ R t . This effect is due to the overlapping of the electric double layer at low values of $$\kappa R_t$$ κ R t .

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“…The insights about the characteristics of the flow field in EOF for a micro-channel/micro or nanopore can also be visualized by the corresponding radial velocity profiles as presented in Figure 6. The velocity profiles in a 2D micro-geometry (micro-channel/nozzle) has been investigated in terms of the Debye length, κR t , Deborah number, De, and rheological constraints by several numerical studies, such as Bezerra et al 56 , Chen et al 45 ,and Mei et al 44 , as well as analytical studies e.g. Afonso et al 50,55 and Wang et al 43 .…”

Section: Volumetric Flow Rate: Effect Of De ε and κR Tmentioning

confidence: 99%

Ion transport in a charged conical nanopore filled with viscoelastic fluids: ion current rectification

Trivedi

¹

,

Nirmalkar

²

2021

Preprint

0

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The ionic current rectification (ICR) is a non-linear current-voltage response upon switching the polarity of the potential across nanopore, similar to the I-V response in the semiconductor diode. The ICR phenomenon finds several potential applications in micro/nano-fluidics (e.g., Bio-sensors and Lab-on-Chip applications). From a biological application viewpoint, most biological fluids (e.g., blood, saliva, mucus, etc.) exhibit non-Newtonian visco-elastic behavior; their rheological properties differ from Newtonian fluids. Therefore, the resultant flow-field should show an additional dependence on the rheological material properties of viscoelastic fluids such as fluid relaxation time (λ) and fluid extensibility (ε). Despite numerous potential applications, the comprehensive investigation of the viscoelastic behavior of the fluid on ionic concentration profile and ICR phenomena has not been attempted. ICR phenomena occur when the length scale and Debye layer thickness approaches of the same order. Therefore, this work extensively investigates the effect of viscoelasticity on the flow and ionic mass transfer along with the ICR phenomena in a single conical nanopore. The Poisson-Nernst-Planck (P-N-P) model coupled with momentum equations have been solved, for a wide range of conditions Deborah number, 1 ≤ De ≤ 100, Debye length parameter, 1 ≤ κRt ≤ 50, fluid extensibility parameter, 0.05 ≤ ε ≤ 0.25, applied electric potential, −40 ≤V ≤ 40, and surface charge density σ = −10 and −50. Four distinct novel characteristics of electro-osmotic flow (EOF) in a conical nanopore have been investigated here, namely (1) detailed structure of flow field and velocity distribution in viscoelastic fluids (2) influence of Deborah number and fluid extensibility parameter on ionic current rectification (ICR) (3) volumetric flow rate calculation as a function of Deborah number and fluid extensibility parameter (4) effect of viscoelastic parameters on concentration distribution of ions in the nanopore. At high applied voltage, both the extensibility parameter and Deborah number facilitate the ICR phenomena. In addition, the ICR phenomena are observed to be more pronounced at low values of κRt than the high values of κRt . This effect is due to the overlapping of the electric double layer at low values of κRt.

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“…In 2019, Tomé et al [ 28 ] presented a solution method for the Giesekus model flow and proposed a new analytical solution for this problem. In 2019, Bezerra et al [ 29 ] used HiG-Flow to perform the solution of electro-osmotic flow of a viscoelastic fluid, where they proposed an approximation for the vortices simulation in a nozzle. Shojaei et al [ 30 ] investigated a generalized finite difference method using the weighted moving least squares procedure, in the same way of our proposed numerical solution.…”

Section: Introductionmentioning

confidence: 99%

A Hierarchical Grid Solver for Simulation of Flows of Complex Fluids

Castelo

¹

,

Afonso

²

,

Bezerra

³

2021

Self Cite

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Tree-based grids bring the advantage of using fast Cartesian discretizations, such as finite differences, and the flexibility and accuracy of local mesh refinement. The main challenge is how to adapt the discretization stencil near the interfaces between grid elements of different sizes, which is usually solved by local high-order geometrical interpolations. Most methods usually avoid this by limiting the mesh configuration (usually to graded quadtree/octree grids), reducing the number of cases to be treated locally. In this work, we employ a moving least squares meshless interpolation technique, allowing for more complex mesh configurations, still keeping the overall order of accuracy. This technique was implemented in the HiG-Flow code to simulate Newtonian, generalized Newtonian and viscoelastic fluids flows. Numerical tests and application to viscoelastic fluid flow simulations were performed to illustrate the flexibility and robustness of this new approach.

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Numerical Study of Electro-Osmotic Fluid Flow and Vortex Formation

Cited by 8 publications

References 34 publications

Ion transport and current rectification in a charged conical nanopore filled with viscoelastic fluids

Ion transport and current rectification in a charged conical nanopore filled with viscoelastic fluids

Ion transport in a charged conical nanopore filled with viscoelastic fluids: ion current rectification

A Hierarchical Grid Solver for Simulation of Flows of Complex Fluids

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