Manipulation of Particle Motions and Their Segregation in Micro-Fluidics by Positive Dielectrophoresis

Materials ◽  
2003 ◽  
Author(s):  
Borus Khusid ◽  
Nikolai Markarian ◽  
Mike Yeksel ◽  
Kenneth R. Farmer ◽  
Andreas Acrivos
Keyword(s):  
Particle Model ◽  
Model Calculations ◽  
Channel Characteristics ◽  
Particle Accumulation ◽  
Micro Fluidics ◽  
Batch Fabrication ◽  
Dilute Suspensions ◽  
Ac Field ◽  
Positive Dielectrophoresis ◽  
Fitting Parameters

We study the ac-field-driven segregation of positively polarized particles flowing through a micro-channel. Our batch fabrication technique allows one to construct an apparatus featuring a large number of mechanically robust and chemically inert micro-devices having a very low ratio of the dielectrophoretic time to the fluid residence time. Experiments were performed on dilute suspensions in microfluidics with electrodes of different sizes arranged parallel and perpendicular to the flow. The application of a high-gradient strong ac field to a flowing suspension results in trapping particles in the channel. When the channel characteristics meet certain requirements, the predictions of a single-particle model for the particle accumulation along the channel are found to be consistent with the experimental data. The model calculations required no fitting parameters because the suspension properties were measured independently. The results of our studies validate a simulation model needed for the design and operation of dielectrophoretic micro-fluidics.

Potential barrier effect and discrete structure o between 40 and 120 Å in the Rb I absorption spectrum

1975 ◽  
Vol 344 (1637) ◽  
pp. 303-309 ◽  
Keyword(s):  
Absorption Spectrum ◽  
Absorption Maximum ◽  
Random Phase Approximation ◽  
Random Phase ◽  
Particle Model ◽  
Discrete Structure ◽  
Model Calculations ◽  
Hartree Fock ◽  
Independent Particle ◽  
Independent Particle Model

Investigation of the Rb I absorption spectrum between 40 and 120 Å has revealed a broad absorption maximum in the 3d photoionization continuum, as well as discrete features associated with the excitation of a 3d-subshell electron. The discrete structure is identified, Hartree-Fock calculations of the transition energies are given and the absorption maximum is discussed in relation to similar spectra and to recent random phase approximation with exchange (r.p.a.e.) and independent particle model calculations.

Prediction of Particle Resuspension and Particle Accumulation in Hydraulic Reservoirs Using Three-Phase CFD Simulations

2019 ◽  
Author(s):  
Lukas Muttenthaler ◽  
Bernhard Manhartsgruber
Keyword(s):  
Particle Diameter ◽  
Free Water ◽  
Solid Particles ◽  
Particle Model ◽  
Hydraulic Systems ◽  
Water Separation ◽  
Particle Resuspension ◽  
Particle Accumulation ◽  
Wide Range ◽  
Oil Flow

Abstract The reduction of hydraulic oil contamination in gaseous (air), liquid (water) and solid (particles) form is highly relevant for hydraulic systems. It minimizes machine downtime, avoids technical failures, and reduces wear of mechanical components and fluid degradation. Particle and water separation are achieved by hydraulic filters. The separation of air bubbles must be undertaken by the reservoir, furthermore the reservoir can support the separation of (free) water and particles. In this paper, stationary results over a wide range of oil flow rates were determined using Eulerian CFD codes. Thus, codes are extended with Lagrangian particle tracking, to determine the size-dependent particle resuspension rate and particle accumulation areas. The results of the particle model were compared and adjusted to experiments, using mineral oil and aluminum oxide test dust. Particle accumulation areas are identified by local deposition distributions for each particle size. An overall distribution was identified by weighting distributions for each particle diameter.

Alpha particle model calculations for 12C and 16O

1974 ◽  
Vol 221 (2) ◽  
pp. 381-391 ◽  
Author(s):  
R.M. Mendez-Moreno ◽  
M. Moreno ◽  
T.H. Seligman
Keyword(s):  
Alpha Particle ◽  
Particle Model ◽  
Model Calculations

scholarly journals A modified shrinking core model for microwave-assisted leaching of aluminum from peat clay

2022 ◽  
Vol 1212 (1) ◽  
pp. 012018
Author(s):  
Hairullah ◽  
A Mirwan ◽  
M D Putra ◽  
B H Ilmanto ◽  
H S H Putri ◽  
...  
Keyword(s):  
Experimental Data ◽  
Aluminum Oxide ◽  
Effective Diffusivity ◽  
Model Calculations ◽  
Reaction Rate Constants ◽  
Microwave Assisted ◽  
Leaching Process ◽  
Water Treatment Process ◽  
Shrinking Core ◽  
Fitting Parameters

Abstract Aluminum oxide in peat clay has the potential to be used as a catalyst, coagulant, and adsorbent for the water treatment process. The usefulness of aluminum oxide in peat clay is enhanced by the leaching process. Aluminum was leached from peat clay in a variety of microwave power, HCl concentrations, and particle size. The effect of the microwave leaching parameters on the aluminum leaching rate was observed. The shrinking core (SC) model used in microwave-assisted leaching was assumed a pseudo steady state with chemical reactions. Effective diffusivity (De), mass transfer coefficient (kc), and reaction rate constants (k) are used as fitting parameters. The best fitting parameters De, kc , and k obtained 0.0049 cm2/s, 2.49 cm/s, and 10.5 cm/s, respectively. The comparison of experimental data and model calculations shown that the SC model can describe experimental data well for all microwave-assisted leaching conditions. Precious information on the results of this research can be given for the goal of the scaling-up and design of the microwave assisted leaching process.

Impact of Ice Cloud Microphysics on Satellite Cloud Retrievals and Broadband Flux Radiative Transfer Model Calculations

2018 ◽  
Vol 31 (5) ◽  
pp. 1851-1864 ◽  
Author(s):  
Norman G. Loeb ◽  
Ping Yang ◽  
Fred G. Rose ◽  
Gang Hong ◽  
Sunny Sun-Mack ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Single Scattering ◽  
Cloud Fraction ◽  
Radiative Transfer Model ◽  
Particle Model ◽  
Transfer Model ◽  
Model Calculations ◽  
Ice Cloud ◽  
Hexagonal Ice ◽  
Thermodynamic Phase

Ice cloud particles exhibit a range of shapes and sizes affecting a cloud’s single-scattering properties. Because they cannot be inferred from passive visible/infrared imager measurements, assumptions about the bulk single-scattering properties of ice clouds are fundamental to satellite cloud retrievals and broadband radiative flux calculations. To examine the sensitivity to ice particle model assumptions, three sets of models are used in satellite imager retrievals of ice cloud fraction, thermodynamic phase, optical depth, effective height, and particle size, and in top-of-atmosphere (TOA) and surface broadband radiative flux calculations. The three ice particle models include smooth hexagonal ice columns (SMOOTH), roughened hexagonal ice columns, and a two-habit model (THM) comprising an ensemble of hexagonal columns and 20-element aggregates. While the choice of ice particle model has a negligible impact on daytime cloud fraction and thermodynamic phase, the global mean ice cloud optical depth retrieved from THM is smaller than from SMOOTH by 2.3 (28%), and the regional root-mean-square difference (RMSD) is 2.8 (32%). Effective radii derived from THM are 3.9 μm (16%) smaller than SMOOTH values and the RMSD is 5.2 μm (21%). In contrast, the regional RMSD in TOA and surface flux between THM and SMOOTH is only 1% in the shortwave and 0.3% in the longwave when a consistent ice particle model is assumed in the cloud property retrievals and forward radiative transfer model calculations. Consequently, radiative fluxes derived using a consistent ice particle model assumption throughout provide a more robust reference for climate model evaluation compared to ice cloud property retrievals.

Numerical Modeling of Micro-Channel Flows by a DPD Method

2003 ◽  
Author(s):  
Justyna Czerwinska ◽  
Nikolaus A. Adams
Keyword(s):  
Molecular Dynamics ◽  
Gas Flow ◽  
Dissipative Particle Dynamics ◽  
Variable Mass ◽  
Coarse Graining ◽  
Voronoi Cell ◽  
Particle Model ◽  
Computational Technique ◽  
Micro Channel ◽  
Micro Fluidics

This paper proposes new computational technique to model micro-flows. The presented below method is based on the meso-scale description of fluid. Dissipative Particle Dynamics (DPD) method is derived from Molecular Dynamics by means of coarse graining procedure. The dissipative particle is defined as a Voronoi cell with variable mass and size; evolves similarly to the Molecular Dynamics particles, except that inter-particle forces have additionally fluctuating, dissipative and stochastic component. This representation leads to the set of equations describing DPD approach. In this paper the outline of the DPD method for application to micro-fluidics flow is presented. DPD method in the form of Soft Fluid Particle model, was mainly applied in material science simulation. This paper presents new approach to model micro-flow by Voronoi Particle DPD method. As a particular example the gas flow in micro-channel flow is computed.

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