Development Of Microdialysis Probes In Series Approach Toward Eliminating Microdialysis Sampling Calibration: Miniaturization Into A Pdms Microfluidic Device, 2018 University of Arkansas, Fayetteville

#### Development Of Microdialysis Probes In Series Approach Toward Eliminating Microdialysis Sampling Calibration: Miniaturization Into A Pdms Microfluidic Device, Randy Espinal Cabrera

*Theses and Dissertations*

A new microdialysis sampling method and microfluidic device were developed in vitro. The method consisted of using up to four microdialysis sampling probes connected in series to evaluate the relative recovery (RR) of different model solutes methyl orange, fluorescein isothiocyanate (FITC)-dextran average mol. wt. 4,000 (FITC-4), FITC-10, FITC-20, and FITC-40. Different flow rates (0.8, 1.0, and 1.5 µL/min) were used to compare experimentally observed relative recoveries with theoretical estimations. With increasing the number of probes in series, the relative recovery increases and ~100% (99.7% ± 0.9%) relative recovery for methyl orange was obtained ...

Mobility Of Nano-Particles In Rock Based Micro-Models, 2018 Louisiana State University

#### Mobility Of Nano-Particles In Rock Based Micro-Models, Jagannath Upadhyay

*LSU Doctoral Dissertations*

A confocal micro-particle image velocimetry (C-μPIV) technique along with associated post-processing algorithms is detailed for obtaining three dimensional distributions of nano-particle velocity and concentrations at select locations of the 2.5D (pseudo 3D) Poly(methyl methacrylate) (PMMA) and ceramic micro-model. The designed and fabricated 2.5D micro-model incorporates microchannel networks with 3D wall structures with one at observation wall which resembles fourteen morphological and flow parameters to those of fully 3D actual reservoir rock (Boise Sandstone) at resolutions of 5 and 10 μm in depth and 5 and 25 μm on plane. In addition, an in-situ, non-destructive method for measuring ...

An Open-Source Quadrature-Based Population Balance Solver For Openfoam, 2018 Iowa State University

#### An Open-Source Quadrature-Based Population Balance Solver For Openfoam, Alberto Passalacqua, Frédérique Laurent, Ehsan Madadi-Kandjani, Jeffrey C. Heylmun, Rodney O. Fox

*Chemical and Biological Engineering Publications*

The extended quadrature method of moments (EQMOM) for the solution of population balance equations (PBE) is implemented in the open-source computational fluid dynamic (CFD) toolbox OpenFOAM as part of the OpenQBMM project. The moment inversion procedure was designed (Nguyen et al., 2016) to maximize the number of conserved moments in the transported moment set. The algorithm is implemented in a general structure to allow the addition of other kernel density functions defined on R+, and arbitrary kernels to describe physical phenomena involved in the evolution of the number density function. The implementation is verified with a set of zero-dimensional cases ...

Effects Of Hofmeister Ions On Gelation Of Gelatin And Pluronic Hydrogels, 2018 The University of Akron

#### Effects Of Hofmeister Ions On Gelation Of Gelatin And Pluronic Hydrogels, Eric Britton

*Honors Research Projects*

The purpose of the project was to observe the effects of the Hofmeister series of ions on the gelation of gelatin and Pluronic-127 hydrogels. Hydrogels are semi-solid materials that contain a network of joined molecules through intermolecular interactions which are capable of holding water. Gelatin and Pluronic-127 (PF-127) are thermoreversible, physical crosslinked gels. Gelation occurs when temperature, or other driving forces, reduce the polymer chain solubility until a distinct 2-phase system forms. When aqueous ions are present in solution, they exhibit specific ion effects that have either a stabilizing or destabilizing effect on the solubility of proteins and other polymers ...

Modeling The Effect Thickener Structure Has On The Oil Release Of Grease, 2018 The University of Akron

#### Modeling The Effect Thickener Structure Has On The Oil Release Of Grease, Dana Cressman

*Honors Research Projects*

Our hypothesis was that the thickener type and micelle concentration of grease affected its viscoelastic properties. Measurements were made using a TA AR G2 rheometer and calculations were made using TA rheometer analysis software to characterize the viscoelastic response of grease under oscillatory shear and frequency tests. The oscillatory frequency tests determined the critical micelle concentration. The oscillatory stress tests were taken at temperatures from 5 to 65 degrees Celsius to create a master curve based on time temperature superposition of the measurements. The crossover points of G’ and G” on the oscillatory stress tests demonstrated where the grease transitions ...

Intermittency Effects On The Universality Of Local Dissipation Scales In Turbulent Boundary Layer Flows With And Without Free-Stream Turbulence, 2018 University of Kentucky

#### Intermittency Effects On The Universality Of Local Dissipation Scales In Turbulent Boundary Layer Flows With And Without Free-Stream Turbulence, Sabah Falih Habeeb Alhamdi

*Theses and Dissertations--Mechanical Engineering*

Measurements of the small-scale dissipation statistics of turbulent boundary layer flows with and without free-stream turbulence are reported for *Re _{τ}* ≈ 1000 (

*Re*≈ 2000). The scaling of the dissipation scale distribution is examined in these two boundary conditions of external wall-bounded flow.

_{θ}Results demonstrated that the local large-scale Reynolds number based on the measured longitudinal integral length-scale fails to properly normalize the dissipation scale distribution near the wall in these two free-stream conditions, due to the imperfect characterization of the upper bound of the inertial cascade by the integral length-scale. When a length-scale based on Townsend's attached-eddy hypothesis ...

Call For Abstracts - Resrb 2018, June 18-20, Brussels, Belgium, 2017 Wojciech Budzianowski Consulting Services

#### Call For Abstracts - Resrb 2018, June 18-20, Brussels, Belgium, Wojciech M. Budzianowski

*Wojciech Budzianowski*

No abstract provided.

Bubble Dynamics And Bed Expansion For Single-Component And Binary Gas-Solid Fluidization Systems, 2017 The University of Western Ontario

#### Bubble Dynamics And Bed Expansion For Single-Component And Binary Gas-Solid Fluidization Systems, Bowen Han

*Electronic Thesis and Dissertation Repository*

Gas-solid fluidized beds are widely used in industrial dry coal preparation to separate waste from coal (still a primarily important energy source worldwide). It is the density difference between coal and the waste that enables the separation. Experiments were carried out in a two dimensional gas-solid fluidized bed. Filtered air at room temperature was used as the fluidizing gas, while magnetite, sand (two types) and FCC catalyst particles belonging to Geldart groups A and B were used as bed particles. Image processing and Matlab were applied for bubble size and velocity measurements. Bubble properties and bed expansion in fluidized beds ...

Simulating Gas-Liquid Flows In An External Loop Airlift Reactor, 2017 Virginia Polytechnic Institute and State University

#### Simulating Gas-Liquid Flows In An External Loop Airlift Reactor, Deify Law, Francine Battaglia, Theodore J. Heindel

*Theodore J. Heindel*

The external loop airlift reactor (ELALR) is a modified bubble column reactor that is composed of two vertical columns that are connected with two horizontal connectors. Airlift reactors are utilized in fermentation processes and are preferred over traditional bubble column reactors because they can operate over a wider range of conditions. Computational fluid dynamics (CFD) simulations can be used to enhance our understanding of the hydrodynamics within these reactors. In the present work, the gas-liquid flow dynamics in an external loop airlift reactor are simulated using CFDLib with an Eulerian-Eulerian ensemble-averaging method in two-dimensional (2D) and three-dimensional (3D) coordinate systems ...

Similitude Analysis For Gas-Liquid-Fiber Flows In Cocurrent Bubble Columns, 2017 Iowa State University

#### Similitude Analysis For Gas-Liquid-Fiber Flows In Cocurrent Bubble Columns, Chengzhi Tang, Theodore J. Heindel

*Theodore J. Heindel*

Gas-liquid-fiber systems are different from conventional gas-liquid-solid systems in that the solid material (i.e., fiber) is flexible, has a large aspect ratio, and forms flocs or networks when its mass fraction is above a critical value. With its wide application to the pulp and paper industry, it is important to investigate the hydrodynamics of gas-liquid-fiber systems. In this paper, 19 parameters that influence gas holdup in gas-liquid-fiber bubble columns are critically examined and then a dimensional analysis based on the Buckingham Pi Theorem is used to derive the dimensionless parameters governing gas-liquid-fiber bubble column hydrodynamics. Seven dimensionless parameters that ...

Stability Issues For Gas-Liquid Flows In Bubble Columns, 2017 Iowa State University

#### Stability Issues For Gas-Liquid Flows In Bubble Columns, Deify Law, Francine Battaglia, Theodore J. Heindel

*Theodore J. Heindel*

In the present work, gas-liquid flow dynamics in a bubble column are simulated with CFDLib using an Eulerian-Eulerian ensemble-averaging method in a two dimensional Cartesian system. The time-averaged gas holdup simulations are compared to experimental measurements of a cylindrical bubble column performed by Rampure et al. [1]. Numerical predictions are presented for the time-averaged gas holdup at various axial heights as a function of radial position. The effects of grid resolution, bubble pressure model, and drag coefficient models on the numerical predictions are examined. The bubble pressure model is reported to account for bubble stability, thus providing physical solutions. The ...

Using X-Rays For Multiphase Flow Visualization, 2017 Iowa State University

#### Using X-Rays For Multiphase Flow Visualization, Theodore J. Heindel, Jeremy L. Hubers, Terrence C. Jensen, Joseph N. Gray, Alexander C. Stiegel

*Theodore J. Heindel*

Gas-liquid, gas-solid, liquid-solid, and gas-liquid-solid multiphase flows are difficult to visualize, characterize, and quantify because the systems are typically opaque. Invasive or noninvasive measurement methods are typically used for determining internal flow and transport characteristics of these complex flows. The difficulty with invasive methods is that they can alter the internal flow of a multiphase system causing interference with realistic process measurements. X-ray imaging provides one family of noninvasive measurement techniques used extensively for product testing and evaluation of static objects with complex structures. These techniques have been extended to visualize dynamic systems, such as those which characterize multiphase flows ...

Repeatability Of Gas Holdup In A Fluidized Bed Using X-Ray Computed Tomography, 2017 Iowa State University

#### Repeatability Of Gas Holdup In A Fluidized Bed Using X-Ray Computed Tomography, Joshua B. Drake, Theodore J. Heindel

*Theodore J. Heindel*

Characterizing the hydrodynamics in fluidized beds is important to many processes from producing biofuels to coating pharmaceuticals. X-ray computed tomography (CT) can quantify local time-averaged phase fractions in multiphase systems that are highly dynamic, like fluidized beds. This paper describes the calibration methods used to produced CT images of a 15.24 cm diameter fluidized bed, how in-house software used these CTs to calculate gas holdup, and how well multiple CTs of a dynamic fluidized bed produced repeatable results while varying bed material and superficial gas velocities. It was concluded there is a very high degree of repeatability using the ...

Gas Holdup In Opaque Cellulose Fiber Slurries, 2017 Iowa State University

#### Gas Holdup In Opaque Cellulose Fiber Slurries, Sarah M. Talcott, Theodore J. Heindel

*Theodore J. Heindel*

Three different cellulose fiber types are used to study their effect on gas holdup and flow regime transition in a 10.2 cm semi-batch bubble column. The three natural fiber types include bleached softwood chemical pulp (softwood), bleached hardwood chemical pulp (hardwood), and bleached softwood chemithermomechanical pulp (BCTMP). Gas holdup is recorded over a range of fiber mass fractions (0 ≤ C ≤ 1.6%) and superficial gas velocities (Ug ≤ 23 cm/s). Experimental results show that gas holdup decreases with increasing fiber mass fraction. Homogeneous, transitional, and heterogeneous flow is observed for all three fiber types at low fiber mass fractions ...

Gas Holdup In A Cocurrent Air-Water-Fiber Bubble Column, 2017 Iowa State University

#### Gas Holdup In A Cocurrent Air-Water-Fiber Bubble Column, Chengzhi Tang, Theodore J. Heindel

*Theodore J. Heindel*

Effects of superficial liquid velocity (Ul ), superficial gas velocity (Ug ), and fiber mass fraction (C) on gas holdup (ε) and flow regime transition are studied experimentally in well-mixed water-cellulose fiber suspensions in a cocurrent bubble column. Experimental results show that the gas holdup decreases with increasing Ul when C and Ug are constant. The gas holdup is not significantly affected by C in the range of C < 0.4%, but decreases with increasing C in the range of 0.4% ≤ C ≤ 1.5%. When C > 1.5%, a significant amount of gas is trapped in the fiber network and recirculates with the water-fiber slurry in the system; as a result, the measured gas holdup is higher than that ...

Numerical Description Of Dilute Particle-Laden Flows By A Quadrature-Based Moment Method, 2017 Office National d'Etudes et de Recherches Aerospatiales, France

#### Numerical Description Of Dilute Particle-Laden Flows By A Quadrature-Based Moment Method, N. Le Lostec, Rodney O. Fox, O. Simonin, P. Villedieu

*Rodney O. Fox*

The numerical simulation of gas-particle flows is divided into two families of methods. In Euler-Lagrange methods individual particle trajectories are computed, whereas in Euler-Euler methods particles are characterized by statistical descriptors. Lagrangian methods are very precise but their computational cost increases with instationarity and particle volume fraction. In Eulerian methods (also called moment methods) the particle-phase computational cost is comparable to that of the fluid phase but requires strong simplificaions. Existing Eulerian models consider unimodal or close-to-equilibrium particle velocity distributions and then fail when the actual distribution is far from equilibrium. Quadrature-based Eulerian methods introduce a new reconstruction of the ...

Treatment Of Fast Chemistry In Fdf/Les: In Situ Adaptive Tabulation, 2017 Iowa State University

#### Treatment Of Fast Chemistry In Fdf/Les: In Situ Adaptive Tabulation, Van Vliet E., Rodney O. Fox, J. J. Derksen, S. B. Pope

*Rodney O. Fox*

The feasibility to implement fast-chemistry reactions in a three-dimensional large eddy simulation (LES) of a turbulent reacting flow using a filtered density function (PDF) technique is studied. Low-density polyethylene (LDPE) is used as an representative reaction due to the stiff nature of the ordinary differential equation (ODE's) describing the kinetics. In FDF/LES, the chemistry needs to be evaluated many times for a large number of fictitious particles that are tracked in the flow, and therefore a constraint is put to the CPU time needed to solve the kinetics. Pope (1997) developed an in situ adaptive tabulation (ISAT) to ...

Effect Of Electrolytes On Co−Water Mass Transfer, 2017 Iowa State University

#### Effect Of Electrolytes On Co−Water Mass Transfer, Haiyang Zhu, Brent H. Shanks, Theodore J. Heindel

*Brent H. Shanks*

The influence of various electrolytes such as sulfate, nitrate, and chloride on CO−water mass transfer was investigated in this study. The results indicate that the enhancement in the CO−water volumetric mass-transfer coefficient ranged from 1.5 to 4.7 times that of a baseline system without electrolytes, depending on electrolyte type and concentration. For those electrolytes with the same anions, copper-containing electrolytes provided stronger enhancement, whereas for those electrolytes with the same cations, sulfate-containing electrolytes showed stronger enhancement. By measuring both the CO−water volumetric mass-transfer coefficient (kLa) and the mass-transfer coefficient (kL), it was found that the ...

Application Of The Fokker-Planck Molecular Mixing Model To Turbulent Scalar Mixing Using Moment Methods, 2017 Iowa State University

#### Application Of The Fokker-Planck Molecular Mixing Model To Turbulent Scalar Mixing Using Moment Methods, Ehsan Madadi-Kandjani, Rodney O. Fox, Alberto Passalacqua

*Chemical and Biological Engineering Publications*

An extended quadrature method of moments using the beta kernel density function (beta-EQMOM) is used to approximate solutions to the evolution equation for univariate and bivariate composition probability distribution functions (PDFs) of a passive scalar for binary and ternary mixing. The key element of interest is the molecular mixing term, which is described using the Fokker-Planck (FP) molecular mixing model. The direct numerical simulations (DNSs) of Eswaran and Pope ["Direct numerical simulations of the turbulent mixing of a passive scalar,"Phys. Fluids 31, 506 (1988)] and the amplitude mapping closure (AMC) of Pope ["Mapping closures for turbulent mixing and reaction ...

Improving Predictive Capabilities Of Classical Cascade Theory For Nonproliferation Analysis, 2017 University of Tennessee, Knoxville

#### Improving Predictive Capabilities Of Classical Cascade Theory For Nonproliferation Analysis, David Allen Vermillion

*Doctoral Dissertations*

Uranium enrichment finds a direct and indispensable function in both peaceful and nonpeaceful nuclear applications. Today, over 99% of enriched uranium is produced by gas centrifuge technology. With the international dissemination of the Zippe archetypal design in 1960 followed by the widespread illicit centrifuge trafficking efforts of the A.Q. Khan network, traditional barriers to enrichment technologies are no longer as effective as they once were. Consequently, gas centrifuge technology is now regarded as a high-priority nuclear proliferation threat, and the international nonproliferation community seeks new avenues to effectively and efficiently respond to this emergent threat.

Effective response first requires ...