A Turbulent Flow without Particle Mixing

Crowe, C. T.; Troutt, T. R.; Chung, J. N.; Davis, Ronald W.; Moore, E. F.

doi:10.1080/02786829408959733

Cited by 14 publications

(12 citation statements)

References 4 publications

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“…The equation of motion of the falling spherical charged particles was developed via force balance under the effect of an external electric field as follows (Crowe et al, 1995; Yang et al, 1993, Jung et al, 2010; Rezvanpour and Wang, 2014):

m_{p} \frac{normald u_{p}}{dt} = \sum boldF = F_{E} + F_{q} + F_{D} + F_{g} + F_{B}

where m p , u p , F E , F q , F D , F g , and F B represent particle mass, particle velocity vector, electric force imposed on the surface of the particles by an external electric field, Coulombic repulsive force, drag force exerted by the surrounding gas, gravitational force, and other body forces, respectively. The body forces include buoyancy force and image force, which is due to the electric force between charged particles and the induced charges on the surface of a conductive collector.…”

Section: Modeling and Simulationmentioning

confidence: 99%

Electrohydrodynamic atomization: A two-decade effort to produce and process micro-/nanoparticulate materials

Xie

Jiang

Davoodi

et al. 2015

Chemical Engineering Science

268

159

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Electrohydrodynamic atomization (EHDA), also called electrospray technique, has been studied for more than one century. However, since 1990s it has begun to be used to produce and process micro-/nanostructured materials. Owing to the simplicity and flexibility in EHDA experimental setup, it has been successfully employed to generate particulate materials with controllable compositions, structures, sizes, morphologies, and shapes. EHDA has also been used to deposit micro- and nanoparticulate materials on surfaces in a well-controlled manner. All these attributes make EHDA a fascinating tool for preparing and assembling a wide range of micro- and nanostructured materials which have been exploited for use in pharmaceutics, food, and healthcare to name a few. Our goal is to review this field, which allows scientists and engineers to learn about the EHDA technique and how it might be used to create, process, and assemble micro-/nanoparticulate materials with unique and intriguing properties. We begin with a brief introduction to the mechanism and setup of EHDA technique. We then discuss issues critical to successful application of EHDA technique, including control of composition, size, shape, morphology, structure of particulate materials and their assembly. We also illustrate a few of the many potential applications of particulate materials, especially in the area of drug delivery and regenerative medicine. Next, we review the simulation and modeling of Taylor cone-jet formation for a single and co-axial nozzle. The mathematical modeling of particle transport and deposition is presented to provide a deeper understanding of the effective parameters in the preparation, collection and pattering processes. We conclude this article with a discussion on perspectives and future possibilities in this field.

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m_{p} \frac{normald u_{p}}{dt} = \sum boldF = F_{E} + F_{q} + F_{D} + F_{g} + F_{B}

Section: Modeling and Simulationmentioning

confidence: 99%

Electrohydrodynamic atomization: A two-decade effort to produce and process micro-/nanoparticulate materials

Xie

Jiang

Davoodi

et al. 2015

Chemical Engineering Science

268

159

View full text Add to dashboard Cite

show abstract

“…The Stokes number characterizes the dispersion of particles due to fluctuating fluid forces encountered in turbulent structures. In order to estimate the effect of turbulent dispersion on particle motion, Crowe [43] proposed to evaluate the Stokes number of the particle, which is the ratio of the particle response time to some time scale related to some time characteristic of the flow field,…”

Section: Stokes Numbermentioning

confidence: 99%

A Numerical Study of Water Injection on Transonic Compressor Rotor Performance

Szabó

2007

45th AIAA Aerospace Sciences Meeting and Exhibit

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In this study, numerical simulations of two-phase flow in a transonic compressor rotor (NASA rotor 37) were performed. Both flow and droplets' governing equations were formulated and solved in the reference frame of the rotating blades. An Eulerian-Lagrangian approach was used for the continuous and discrete phases with a two-way interaction model to simulate the mass-, momentum-and energy exchange between the different phases. Water particles were injected at the inlet with uniform particle mass flux, fully evaporating inside the rotating blade row. The phase change was most intense in areas adjacent to shock waves, where the slip velocity of the droplets was the highest. Results show decreased circumferentially averaged total temperature ratio of the air-vapor mixture across the span, which is the direct result of inter-phase energy coupling. An entropy based approach to calculate the isentropic efficiency of a wet compression process in a transonic compressor rotor was also presented. Under the proposed method, the viscous dissipation function was calculated everywhere in the domain in the post-processing phase of the numerical simulation and integrated to the wall, with special treatment in the nearwall regions where high rates of entropy generation occur. For a water to air mass flow ratio of 1% results show increased entropy production across the span, resulting in a 5% drop in compressor isentropic efficiency. Analytical integration of wall functions and numerical integration of the viscous dissipation function allows for reasonable results even with relatively coarse grids and can also be applied for single-phase flows. A parametric study of the effect of initial particle parameters on the wet compression process was also performed. Several speedlines have been computed with different amounts of water, especially near the tip. Results show that numerical stall can be delayed with injection of water near the tip, due to the increase of the axial momentum of the fluid in the endwall region, which is the direct result of phase change.iv v ACKNOWLEDGEMENT

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“…In fact, this approach to the analysis of particle motion subject to a force field, which in turn depends on fields defined by a numerical simulation on some kind of discrete grid, is applicable to a wide class of dilute gas-particle flow problems. This class even includes transient flows such as particle mixing in wakes (Crowe et al, 1995) and mixing layers (see Marcu and Meiburg (1996), who also use a dynamical systems approach). Finally, it is noted that dynamical systems theory has also proven very useful in the analysis of flow patterns in single-phase fluid flows (Perry and Chong, 1987;Ottino, 1989).…”

Section: Introductionmentioning

confidence: 99%

Dynamical Systems Approach to Particle Transport Modeling in Dilute Gas-Particle Flows with Application to a Chemical Vapor Deposition Reactor

Burns

Davis

Moore

1997

Aerosol Science and Technology

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A general method for treating the transport of particles in dilute gas-particle flows is presented. This method formulates the particle transport equations as a dynamical system, and utilizes the corresponding theory to analyze the resulting dynamics. As an illustration of this technique, the transport of contaminant particles in a barrel-type CVD reactor is analyzed. The background gas flow field is determined via a numerical simulation of the Navier-Stokes equations. The analysis reveals the presence of particle attractors in the flow which are particle size specific. The features of these attractors are discussed, as is their behavior with varying particle size.

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A Turbulent Flow without Particle Mixing

Cited by 14 publications

References 4 publications

Electrohydrodynamic atomization: A two-decade effort to produce and process micro-/nanoparticulate materials

Electrohydrodynamic atomization: A two-decade effort to produce and process micro-/nanoparticulate materials

A Numerical Study of Water Injection on Transonic Compressor Rotor Performance

Dynamical Systems Approach to Particle Transport Modeling in Dilute Gas-Particle Flows with Application to a Chemical Vapor Deposition Reactor

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