scholarly journals Enhancement of Heterogeneous Microfluidic Immunosensors Using New Sensing Area Shape with Electrothermal Effect

2021 ◽  
Vol 11 (10) ◽  
pp. 4566
Author(s):  
Fraj Echouchene ◽  
Thamraa Al-shahrani ◽  
Hafedh Belmabrouk
Keyword(s):  
Three Dimensional ◽  
Critical Factor ◽  
Circular Ring ◽  
Navier Stokes ◽  
Initial Slope ◽  
Surface Design ◽  
Reactive Protein ◽  
Reaction Surface ◽  
Microfluidic Biosensor ◽  
Dimensional Simulation

In heterogeneous microfluidic immunosensors, the diffusion boundary layer produced on the sensing area represents a critical factor that limits the biosensor performance. A three-dimensional simulation using the finite element method on the binding reaction kinetics of C-reactive protein (CRP) has been performed. We present a new microfluidic biosensor based on a novel reaction-surface design without and with electrothermal force. Two reaction surface configurations were studied. The kinetic reaction rate was calculated with coupled Navier−Stokes, mass diffusion, energy, and Laplace equations. The numerical results reveal that the characteristics of a microfluidic biosensor are more enhanced by using the circular ring design of the sensing area coupled with the electrothermal force. The rate of initial slope related to the association phase is multiplied by a factor 2 when the voltage is increased from 10 to 15 V. The results prove to be valuable in designing new microfluidic biosensors.

scholarly journals Analysis of Temperature-Jump Boundary Conditions on Heat Transfer for Heterogeneous Microfluidic Immunosensors

Sensors ◽  
2021 ◽  
Vol 21 (10) ◽  
pp. 3502
Author(s):  
Fraj Echouchene ◽  
Thamraa Al-shahrani ◽  
Hafedh Belmabrouk
Keyword(s):  
Heat Transfer ◽  
Temperature Jump ◽  
Three Dimensional ◽  
Accommodation Coefficient ◽  
Circular Ring ◽  
The Other ◽  
Effect Of Temperature ◽  
Navier Stokes ◽  
Microfluidic Biosensor ◽  
Dimensional Simulation

The objective of the current study is to analyze numerically the effect of the temperature-jump boundary condition on heterogeneous microfluidic immunosensors under electrothermal force. A three-dimensional simulation using the finite element method on the binding reaction kinetics of C-reactive protein (CRP) was performed. The kinetic reaction rate was calculated with coupled Laplace, Navier−Stokes, energy, and mass diffusion equations. Two types of reaction surfaces were studied: one in the form of a disc surrounded by two electrodes and the other in the form of a circular ring, one electrode is located inside the ring and the other outside. The numerical results reveal that the performance of a microfluidic biosensor is enhanced by using the second design of the sensing area (circular ring) coupled with the electrothermal force. The improvement factor under the applied ac field 15 Vrms was about 1.2 for the first geometry and 3.6 for the second geometry. Furthermore, the effect of temperature jump on heat transfer rise and response time was studied. The effect of two crucial parameters, viz. Knudsen number (Kn) and thermal accommodation coefficient (σT) with and without electrothermal effect, were analyzed for the two configurations.

Direct simulation of evolution and control of three-dimensional instabilities in attachment-line boundary layers

1995 ◽  
Vol 291 ◽  
pp. 369-392 ◽  
Author(s):  
Ronald D. Joslin
Keyword(s):  
Boundary Layer ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Plate Boundary ◽  
Navier Stokes ◽  
Two Dimensional ◽  
Computationally Efficient ◽  
Simulation Results ◽  
Dimensional Simulation ◽  
Attachment Line

The spatial evolution of three-dimensional disturbances in an attachment-line boundary layer is computed by direct numerical simulation of the unsteady, incompressible Navier–Stokes equations. Disturbances are introduced into the boundary layer by harmonic sources that involve unsteady suction and blowing through the wall. Various harmonic-source generators are implemented on or near the attachment line, and the disturbance evolutions are compared. Previous two-dimensional simulation results and nonparallel theory are compared with the present results. The three-dimensional simulation results for disturbances with quasi-two-dimensional features indicate growth rates of only a few percent larger than pure two-dimensional results; however, the results are close enough to enable the use of the more computationally efficient, two-dimensional approach. However, true three-dimensional disturbances are more likely in practice and are more stable than two-dimensional disturbances. Disturbances generated off (but near) the attachment line spread both away from and toward the attachment line as they evolve. The evolution pattern is comparable to wave packets in flat-plate boundary-layer flows. Suction stabilizes the quasi-two-dimensional attachment-line instabilities, and blowing destabilizes these instabilities; these results qualitatively agree with the theory. Furthermore, suction stabilizes the disturbances that develop off the attachment line. Clearly, disturbances that are generated near the attachment line can supply energy to attachment-line instabilities, but suction can be used to stabilize these instabilities.

scholarly journals Three-Dimensional Simulation of Fluid–Structure Interaction Problems Using Monolithic Semi-Implicit Algorithm

Fluids ◽  
2019 ◽  
Vol 4 (2) ◽  
pp. 94 ◽  
Author(s):  
Cornel Marius Murea
Keyword(s):  
Stokes Equations ◽  
Fluid Structure Interaction ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Arbitrary Lagrangian Eulerian ◽  
Time Step ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Dimensional Simulation ◽  
Updated Lagrangian

A monolithic semi-implicit method is presented for three-dimensional simulation of fluid–structure interaction problems. The updated Lagrangian framework is used for the structure modeled by linear elasticity equation and, for the fluid governed by the Navier–Stokes equations, we employ the Arbitrary Lagrangian Eulerian method. We use a global mesh for the fluid–structure domain where the fluid–structure interface is an interior boundary. The continuity of velocity at the interface is automatically satisfied by using globally continuous finite element for the velocity in the fluid–structure mesh. The method is fast because we solve only a linear system at each time step. Three-dimensional numerical tests are presented.

Preliminary Results of Numerical Simulations of a Bio-Mimetic Wells Turbine

2016 ◽  
Author(s):  
Qiuhao Hu ◽  
Ye Li ◽  
Fangyi Wei
Keyword(s):  
Energy Conversion ◽  
Three Dimensional ◽  
Turbine Rotor ◽  
Navier Stokes ◽  
Maximum Efficiency ◽  
Wells Turbine ◽  
Turbulence Effects ◽  
Dimensional Simulation ◽  
Lower Torque ◽  
Good Agreement

Wells turbine is a kind of self-rectified air turbines used in an oscillatory water column (OWC) device for wave energy conversion. In this study, a steady three-dimensional simulation of a fan-shaped Wells turbine is performed on Star CCM+ commercial software by solving the Reynolds-averaged Navier-Stokes (RANS) equations. The turbulence effects are taken into account by using the Spalart-Allmaras turbulence model. Good agreement between the numerical results and the experimental results within the operation region (5< α <11 degrees) is observed. The geometry of the turbine rotor has a significant effect on the performance of energy conversion. Inspired by the aerodynamics of low Reynolds flyer, the normal fan-shaped Wells turbine is optimized by a bio-mimetic method in which the profile of a hawk moth wing of Manduca Sexta is applied on the blades. The modified turbine has a lower torque and pressure drop coefficient with higher efficiency. The maximum efficiency for the modified turbine is 0.61, compared to 0.48 for the normal fan-shaped one. By analysis of the detailed flow-field, it has also been found that only the middle parts of the blade can effectively generate the momentum. In order to acquire a higher efficiency, further optimization is carried out by refining some blade parts in the tip and the hub which cannot effectively produce power.

Three-Dimensional Simulation of Laminar Rectangular Impinging Jets, Flow Structure, and Heat Transfer

1999 ◽  
Vol 121 (1) ◽  
pp. 50-56 ◽  
Author(s):  
I. Sezai ◽  
A. A. Mohamad
Keyword(s):  
Heat Transfer ◽  
Three Dimensional ◽  
Streamwise Velocity ◽  
Impinging Jets ◽  
Navier Stokes ◽  
Aspect Ratios ◽  
Laminar Jets ◽  
Nusselt Number Distribution ◽  
Dimensional Simulation ◽  
Energy Equations

The flow and heat transfer characteristics of impinging laminar jets issuing from rectangular slots of different aspect ratios have been investigated numerically through the solution of three-dimensional Navier-Stokes and energy equations in steady state. The three-dimensional simulation reveals the existence of pronounced streamwise velocity off-center peaks near the impingement plate. Furthermore, the effect of these off-center velocity peaks on the Nusselt number distribution is also investigated. Interesting three-dimensional flow structures are detected which cannot be predicted by two-dimensional simulations.

scholarly journals Design, Optimization and Analysis of Supersonic Radial Turbines

2019 ◽  
Author(s):  
Lukas Benjamin Inhestern ◽  
James Braun ◽  
Guillermo Paniagua ◽  
José Ramón Serrano Cruz
Keyword(s):  
High Performance ◽  
Ad Hoc ◽  
Three Dimensional ◽  
Critical Factor ◽  
Design Tool ◽  
Navier Stokes ◽  
Design Parameters ◽  
Design Variables ◽  
Compact Design ◽  
Radial Outflow

Abstract New compact engine architectures such as pressure gain combustion require ad-hoc turbomachinery to ensure an adequate range of operation with high performance. A critical factor for supersonic turbines is to ensure the starting of the flow passages, which limits the flow turning and airfoil thickness. Radial outflow turbines inherently increase the cross section along the flow path, which holds great potential for high turning of supersonic flow with a low stage number and guarantees a compact design. First the preliminary design space is described. Afterwards a differential evolution multi-objective optimization with 12 geometrical design parameters is deducted. With the design tool AutoBlade 10.1, 768 geometries were generated and hub, shroud, and blade camber line were designed by means of Bezier curves. Outlet radius, passage height, and axial location of the outlet were design variables as well. Structured meshes with around 3.7 million cells per passage were generated. Steady three dimensional Reynolds averaged Navier Stokes (RANS) simulations, enclosed by the k-omega SST turbulence model were solved by the commercial solver CFD++. The geometry was optimized towards low entropy and high power output. To prove the functionality of the new turbine concept and optimization, a full wheel unsteady RANS simulation of the optimized geometry exposed to a nozzled rotating detonation combustor (RDC) has been performed and the advantageous flow patterns of the optimization were also observed during transient operation.

The dynamics of breaking internal solitary waves on slopes

2014 ◽  
Vol 761 ◽  
pp. 360-398 ◽  
Author(s):  
Robert S. Arthur ◽  
Oliver B. Fringer
Keyword(s):  
Reynolds Number ◽  
Velocity Structure ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Mixing Efficiency ◽  
Streamwise Vorticity ◽  
Initial Wave ◽  
Reynolds Number Effects ◽  
Dimensional Simulation ◽  
Dimensional Domain

AbstractUsing direct numerical simulations (DNS), we investigate the structure and energetics of breaking internal waves on slopes. We employ a Navier–Stokes code in an idealized three-dimensional domain where an internal solitary wave of depression impinges upon a sloping bottom. Seven cases with varying initial wave amplitude and bathymetric slope, but constant wave Reynolds number $\mathit{Re}_{w}$ are considered. Volume-integrated values of dissipation and irreversible mixing are related to the density and velocity structure of the wave throughout the breaking process. The majority of dissipation (63 %) occurs along the no-slip bottom boundary. Most of the remaining dissipation (35 %) and nearly all irreversible mixing occurs in the interior after breaking, when density overturns are present at the interface. Breaking introduces three-dimensionality to the flow field that is driven by the lateral breakdown of density overturns and the lobe–cleft instability typical of gravity currents. The resulting longitudinal rolls (streamwise vorticity) increase dissipation by roughly 8 % and decrease irreversible mixing by roughly 20 % when compared with a similar two-dimensional simulation. The bulk mixing efficiency is shown to increase for larger and smaller values of the internal Iribarren number ${\it\xi}$, with a minimum for intermediate values of ${\it\xi}$ and a peak near ${\it\xi}=0.8$ for plunging breakers. This trend is explained by the degree of two-dimensionality in the flow, and agrees with previous results in the literature after accounting for Reynolds number effects. Local turbulence quantities are also calculated at ‘virtual moorings’, and a location upslope of the breakpoint but downslope of the intersection of the pycnocline and the bottom is shown to provide a signal that is most representative of the volume-integrated dissipation and mixing results.

Three Dimensional Simulation of Bore Flow Using SPH

2010 ◽  
Author(s):  
Huaxing Liu ◽  
Soon Keat Tan ◽  
Jing Li ◽  
Xikun Wang
Keyword(s):  
High Speed ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Smooth Particle Hydrodynamic ◽  
Navier Stokes ◽  
Initial Water ◽  
Navier Stokes Equations ◽  
Sph Model ◽  
Complex Fluid ◽  
Dimensional Simulation

Tidal bore is a fascinating and powerful hydraulic phenomenon. In this paper, the tidal bore’s process is studied using 3D Smooth Particle Hydrodynamic (SPH) model. The Lagrangian nature of SPH suits well to the modeling of the complex fluid flow phenomenon. In the SPH method, the Navier-Stokes equations are discretized with fluid particles in the Lagrangine sense. Boundary conditions, including both no slip wall and bottom wall, are implemented using dynamic boundary particles. Using SPH, the bore’s generation together with its traverse along the channel are presented, including the description of flow field and bore’s configuration. Different types of bores’ behavior are investigated. It is observed that there is a splash of water surge up the wall and the front of the bore becomes a breaker wave when the initial water column travels at high speed. The velocity field and bore heights at different locations are visualized and discussed as well.

scholarly journals Flux correlations in supersonic isothermal turbulence

2012 ◽  
Vol 713 ◽  
pp. 482-490 ◽  
Author(s):  
R. Wagner ◽  
G. Falkovich ◽  
A. G. Kritsuk ◽  
M. L. Norman
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Compressible Turbulence ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Barotropic Fluids ◽  
Gravity Driven ◽  
Dimensional Simulation ◽  
Using Data ◽  
Astrophysical Flows

AbstractUsing data from a large-scale three-dimensional simulation of supersonic isothermal turbulence, we have tested the validity of an exact flux relation derived analytically from the Navier–Stokes equation by Falkovich, Fouxon & Oz (J. Fluid Mech., vol. 644, 2010, p. 465). That relation, for compressible barotropic fluids, was derived assuming turbulence generated by a large-scale force. However, compressible turbulence in simulations is usually initialized and maintained by a large-scale acceleration, as in gravity-driven astrophysical flows. We present a new approximate flux relation for isothermal turbulence driven by a large-scale acceleration, and find it in reasonable agreement with the simulation results.

scholarly journals Three-dimensional simulation of flows in practical water-pump intakes

2006 ◽  
Vol 8 (2) ◽  
pp. 111-124 ◽  
Author(s):  
Songheng Li ◽  
Jose Matos Silva ◽  
Yong Lai ◽  
Larry J. Weber ◽  
V. C. Patel
Keyword(s):  
Three Dimensional ◽  
Streamwise Velocity ◽  
Navier Stokes ◽  
Water Pump ◽  
Cfd Model ◽  
Scaled Model ◽  
Model Flow ◽  
Flow Features ◽  
Entire Flow ◽  
Dimensional Simulation

The potential to use a three-dimensional (3D) computational fluid dynamics (CFD) model to produce the complexity of the flows in water-pump intakes and the prospects to use it as an effective assistant in the design or fixing of the related problems are reported. A scaled model of a real water-pump intake with flow conditions corresponding to the prototype was selected and studied. The Reynolds number of the model flow is 120 000, based on the diameter and bulk velocity in the pump column. The 3D CFD model solves the Reynolds averaged Navier–Stokes (RANS) equations with the k–ɛ turbulence model with wall function. A multi-block structured mesh was used. Numerical simulations are processed to reveal the important flow features in the entire flow field, compare the streamwise velocity distribution in the approaching channel, at and above the pump throat, as well as the swirl of flow at the pump throat. Numerical results provide insights into the complexity of flow around and inside the pump column under different incoming flows. This study makes significant strides from a simple intake to a real one and shows good prospects of further use of this 3D model to simulate flows in practical water-pump intakes.

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