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Full-Text Articles in Biomedical Engineering and Bioengineering

Strongly Coupled Fluid-Particle Flows In Vertical Channels. I. Reynolds-Averaged Two-Phase Turbulence Statistics, Jesse Capecelatro, Olivier Desjardins, Rodney O. Fox Mar 2016

Strongly Coupled Fluid-Particle Flows In Vertical Channels. I. Reynolds-Averaged Two-Phase Turbulence Statistics, Jesse Capecelatro, Olivier Desjardins, Rodney O. Fox

Chemical and Biological Engineering Publications

Simulations of strongly coupled (i.e., high-mass-loading) fluid-particle flows in vertical channels are performed with the purpose of understanding the fundamental physics of wall-bounded multiphase turbulence. The exact Reynolds-averaged (RA) equations for high-mass-loading suspensions are presented, and the unclosed terms that are retained in the context of fully developed channel flow are evaluated in an Eulerian–Lagrangian (EL) framework for the first time. A key distinction between the RA formulation presented in the current work and previous derivations of multiphase turbulence models is the partitioning of the particle velocity fluctuations into spatially correlated and uncorrelated components, used to define the ...


Strongly Coupled Fluid-Particle Flows In Vertical Channels. Ii. Turbulence Modeling, Jesse Capecelatro, Olivier Desjardins, Rodney O. Fox Jan 2016

Strongly Coupled Fluid-Particle Flows In Vertical Channels. Ii. Turbulence Modeling, Jesse Capecelatro, Olivier Desjardins, Rodney O. Fox

Chemical and Biological Engineering Publications

In Part I, simulations of strongly coupled fluid-particle flow in a vertical channel were performed with the purpose of understanding, in general, the fundamental physics of wall-bounded multiphase turbulence and, in particular, the roles of the spatially correlated and uncorrelated components of the particle velocity.The exact Reynolds-averaged (RA) equations for high-mass-loading suspensions were presented, and the unclosed terms that are retained in the context of fully developed channel flow were evaluated in an Eulerian–Lagrangian (EL) framework. Here, data from the EL simulations are used to validate a multiphase Reynolds-stress model (RSM) that predicts the wall-normal distribution of the ...


A Hierarchy Of Eulerian Models For Trajectory Crossing In Particle-Laden Turbulent Flows Over A Wide Range Of Stokes Numbers, Frederique Laurent, Aymeric Vie, Christophe Chalons, Rodney O. Fox, Marc Massot Jan 2013

A Hierarchy Of Eulerian Models For Trajectory Crossing In Particle-Laden Turbulent Flows Over A Wide Range Of Stokes Numbers, Frederique Laurent, Aymeric Vie, Christophe Chalons, Rodney O. Fox, Marc Massot

Chemical and Biological Engineering Publications

With the large increase in available computational resources, large-eddy simulation (LES) of industrial configurations has become an efficient and tractable alternative to traditional multiphase turbulence models. Many applications involve a liquid or solid disperse phase carried by a gas phase (eg, fuel injection in automotive or aeronautical engines, fluidized beds, and alumina particles in rocket boosters).


A Quadrature-Based Kinetic Model For Dilute Non-Isothermal Granular Flows, Alberto Passalacqua, Janine E. Galvin, Prakash Vedula, Christine M. Hrenya, Rodney O. Fox Jul 2011

A Quadrature-Based Kinetic Model For Dilute Non-Isothermal Granular Flows, Alberto Passalacqua, Janine E. Galvin, Prakash Vedula, Christine M. Hrenya, Rodney O. Fox

Chemical and Biological Engineering Publications

A moment method with closures based on Gaussian quadrature formulas is proposed to solve the Boltzmann kinetic equation with a hard-sphere collision kernel for mono-dispersed particles. Different orders of accuracy in terms of the moments of the velocity distribution function are considered, accounting for moments up to seventh order. Quadrature-based closures for four different models for inelastic collisionthe Bhatnagar-Gross-Krook, ES-BGK, the Maxwell model for hard-sphere collisions, and the full Boltzmann hard-sphere collision integral-are derived and compared. The approach is validated studying a dilute non-isothermal granular flow of inelastic particles between two stationary Maxwellian walls. Results obtained from the kinetic models ...


A Multi-Gaussian Quadrature Method Of Moments For Simulating High Stokes Number Turbulent Two-Phase Flows, Aymeric Vie, Christophe Chalons, Rodney O. Fox, Frederique Laurent, Marc Massot Jan 2011

A Multi-Gaussian Quadrature Method Of Moments For Simulating High Stokes Number Turbulent Two-Phase Flows, Aymeric Vie, Christophe Chalons, Rodney O. Fox, Frederique Laurent, Marc Massot

Chemical and Biological Engineering Publications

With the great increase in computational resources, Large Eddy Simulation (LES) of industrial configurations is now an efficient and tractable tool. Numerous applications involve a liquid or solid disperse phase carried by a gaseous flow field (eg, fuel injection in automotive or aeronautical engines, fluidized beds, and alumina particles in rocket boosters). To simulate this kind of flow, one may resort to a Number Density Function (NDF), which satisfies a kinetic equation.


Quadrature-Based Moment Model For Moderately Dense Polydisperse Gas-Particle Flows, Rodney O. Fox, Prakash Vedula Jan 2010

Quadrature-Based Moment Model For Moderately Dense Polydisperse Gas-Particle Flows, Rodney O. Fox, Prakash Vedula

Chemical and Biological Engineering Publications

A quadrature-based moment model is derived for moderately dense polydisperse gas-particle flows starting from the inelastic Boltzmann-Enskog kinetic equation including terms for particle acceleration (e.g., gravity and fluid drag). The derivation is carried out for the joint number density function, f(t,x,m,u), of particle mass and velocity, and thus, the model can describe the transport of polydisperse particles with size and density differences. The transport equations for the integer moments of the velocity distribution function are derived in exact form for all values of the coefficient of restitution for particle-particle collisions. For particular limiting cases, the ...


Multiscale Modeling Of Tio2 Nanoparticle Production In Flame Reactors: Effect Of Chemical Mechanism, Maulik Mehta, Yonduck Sung, Venkatramanan Raman, Rodney O. Fox Jan 2010

Multiscale Modeling Of Tio2 Nanoparticle Production In Flame Reactors: Effect Of Chemical Mechanism, Maulik Mehta, Yonduck Sung, Venkatramanan Raman, Rodney O. Fox

Chemical and Biological Engineering Publications

For titanium dioxide (TiO2) nanoparticles manufactured in flame reactors, the precursor is injected into a pre-existing flame, exposing it to a high-temperature gas phase, leading to nucleation and particle growth. Predictive modeling of this chemical process requires simultaneous development of detailed chemical mechanisms describing gas-phase combustion and particle evolution, as well as advanced computational tools for describing the turbulent flow field and its interactions with the chemical processes. Here, a multiscale computational tool for flame-based TiO2 nanoparticle synthesis is developed and a flamelet model representing detailed chemistry for particle nucleation is proposed. The effect of different chemical mechanisms ...