Turbulent heat or mass transfer (National Science Foundation CTS-0209758, CBET-0651180; National Center for Supercomputing Applications and TeraGrid, CTS990021N, CTS010024, CTS040023, CTS070050)

Direct Numerical Simulations of turbulent flows with passive heat transfer will provide results needed to test the present theory and to suggest new approaches. Of particular importance will be the possibility of relating transport at different Prandtl numbers, Pr, to turbulence structure. This simulation will provide accurate results for small Pr (e.g., air with Pr=0.7, and liquid metals with Pr<0.1). In addition, turbulent reactive flows and the effect of a chemical reaction on the mass transfer properties will be investigated.

Lagrangian simulation of scalar transport in wall turbulence (National Science Foundation, CTS-0209758, CBET-0651180)

In the Lagrangian framework, the system of reference moves with the fluid particles, or the heat or mass markers in the case of turbulent transport. In order to apply this methodology, information along the trajectories of heat or mass markers must be known. A tracking algorithm is used to monitor the trajectories of these markers in space and time as they move in a hydrodynamic field created by a Direct Numerical Simulation. At first, the fluid structures that enhance mixing of heat or mass markers and move them away from the viscous wall region will be investigated. The effect of molecular Prandtl or Schmidt number will also be studied. A major advantage of this approach will be the capability of describing turbulent heat of mass transfer with a variety of configurations (line source, heated plate, step change in the temperature of the wall, heated channel) with a very limited number of numerical experiments.

Heat transport in carbon nanotube composite materials (Department of Energy, DE-FG02-06ER64239)

Carbon nanotube composite materials did not live up to expectations regarding enhanced thermal properties. Even though single-walled and multi-walled carbon nanotubes (CNTs) have thermal conductivities that are on par with the most thermally conductive materials known, composites with carbon nanotube inclusions exhibit effective thermal conductivities that are controlled by the thermal resistance for heat transfer at the nanotube-matrix material interface. We are exploring the effects of the interfacial thermal resistance to heat transfer on the effective conductivity of CNT composites and CNT suspensions. We have developed a Monte Carlo algorithm that can predict the effective thermal conductivity of the composite and can be used to study the effects of the CNT volume fraction and orientation on the thermal conductivity. The challenge is to improve the composite properties by exploring the mechanisms that result in the appearance of the thermal resistance. We are collaborating with other researchers at OU (Profs. Brian Grady, Alberto Striolo, Kieran Mullen, Daniel Resasco) as well as researchers in other institutions (Prof. Shigeo Maruyama at the U. of Tokyo and Prof. Brian Wardle at MIT).

Flow effects on porous scaffolds for tissue regeneration (National Science Foundation, CBET-0700813; TeraGrid CTS080042)

The objective of this work is to examine the effects of fluid flow in the form of convective perfusion through porous scaffolds widely used in tissue engineering applications. The goal is to characterize the fluid dynamic environment at the interior of three-dimensional porous scaffolds and its effects on the behavior of seeded bone cells. Such fundamental understanding, from both experimental and theoretical perspectives, is critical to the long term success of tissue engineering strategies that use cell/scaffold constructs as implants. In collaboration with Prof. Sikavitsas, we investigate the effect of convective flow perfusion in 3D scaffolds having complex porous architectures on the in vitro generated extracellular matrix, and we are working to identify the critical flow rate where excessive detachment of cells occurs.    We are also using lattice Boltzmann methods to characterize in detail the fluid flow environment within the porous scaffold, while the 3D configuration changes continuously due to tissue growth, in order to develop a theoretical framework for the prediction of the applied shear forces in each location. Our Lagrangian numerical methodology will also be employed to investigate the formation of the concentration field of nutrients within the scaffold ant to explore the concentration gradients that are critical for tissue growth.

Simulation of the flow field that results from two rectangular jets (National Science Foundation, The 3M Company, Nordson Corporation, NSF-DMII-0245324 )

The commercially important process of fiber melt blowing will be described with an experimentally-verified model.  Melt blowing involves the impact of high velocity air streams upon a molten polymer to form fine webs of fiber.  In recent years, Prof. Shambaugh’s group developed a model for describing the polymer side behavior.  In this model, the air field enters the equation solutions as a boundary condition.  The model is very good, but sometimes its predictions are only semi-quantitative.  Very recently, our research group in collaboration with Prof. Shambaugh’s group has used a commercial computational fluid dynamics software package (FLUENT); this CFD work gives much more information about the air field than was previously available.  We will combine the CFD work (to describe the air side) with the previously developed model for the polymer side.  The goal is to develop an accurate, comprehensive model for melt blowing. 

Development of learning tools to bridge Economics with Chemical Engineering (National Science Foundation, DUE-0737182)

This collaborative project with Prof. Kosmopoulou aims to bring modern techniques that are well-developed in the field of Economics and Management into the Chemical Engineering classroom, and more specifically into the Chemical Engineering Design and Engineering Economics curriculum. The goal is to develop learning material combining economics and chemical engineering in the form of illustrative examples, classroom experiments, homework problems, and lecture notes. This material will be adopted in existing courses during the currently funded Phase 1 of this project. Selected parts of it will be used for the integration of concepts from the two disciplines in a new course during Phase 2 of the project, funding for which will be solicited through the CCLI program in 2010.

Turbulent drag reduction with macromolecular brushes (Office of Naval Research, N00014-03-1-0684)

The development of the methodology for friction drag reduction is a subject of ongoing interest to the Navy.  One of the current research thrusts is the use of polymers/surfactants and microbubbles in the near-wall region to promote a reduction in the wall shear stress, and hence in the friction drag.  An alternate solution that does not involve the continuous addition of surfactant/polymers or microbubbles is proposed in this project. The idea of surface-mounted polymer chains and nanotubes to modify the near-wall flow field and hence the wall shear stress is proposed.  The aim is to provide a physical understanding of the mechanics of drag reduction by this method and to demonstrate the practical viability of the proposed method. 

A combined experimental and computational approach is taken.  Experiments will be carried out in a fully-developed channel flow facility in which the walls can be easily replaced. Wall shear stress measurements will be made with walls coated with different densities of polymer chains/nanotubes (Dr. Newman’s lab).  Non-intrusive velocity measurements will be made using laser Doppler velocimetry (LDV) and Particle Image Velocimetry (PIV) to document the modifications in the flow structure in the near-wall region (Prof. Parthasarathy’s group).  Direct numerical simulations (DNS) of the channel flow will be undertaken by our grooup.  In addition, molecular simulations have been conducted to provide input to the DNS (Prof. Lloyd Lee’s group).  

Transport processes in microchannels with nanotube brushes (National Science Foundation, Nanonet, NSF-EPS-0132354)

Carbon nanotubes exhibit properties that promise to revolutionize technology in the next few decades. One of these properties is very high thermal conductivity. This project will investigate the heat transport behavior of surfaces that are covered with carbon nanotubes. Microchannels with arrangements of nanotubes are particularly interesting, because of the potential applications for heat dissipation in microchips. The objective is to explore the feasibility of designing micro-heat exchangers that will utilize nanotubes as heat conductors.

Scalar transport through porous media (Petroleum Research Fund, ACS-PRF# 39455-AC9)

Fairly little information of general applicability is known about scalar transfer in heterogeneous, dense media. We are studying the transport of a scalar in porous media using flow simulations at small scales in conjunction with the Lagrangian scalar tracking method developed by our laboratory for other types of flow (i.e., for turbulence). The hypothesis is that the medium structure and the fluid properties are needed to predict the scalar profile in the flow domain. Different numerical methods, each one appropriate for a particular physical scale, is utilized for the flow field. Flow in the pore scale will be simulated with the Lattice Boltzmann Method, initially through unconsolidated media and later using digital images of actual rocks as the flow domain. Furthermore, pore network modeling and stochastic methods will be used for the systematic study of the effects of the medium structure on the transport properties at larger physical scales.

Multiphase flow through porous media (Mobil Technology Company, Petroleum Research Fund, ACS-PRF# 35103-G9)

The goal is the macroscopic modeling of reservoir behavior by using novel computational techniques and by incorporating more physics into the problem. The result will be a new more realistic reservoir simulator. State of the art reservoir simulators use Darcy’s law to predict pressure drop in reservoirs far from the well and a skin factor close to the well, which models linearly the non-Darcy pressure drop. A further assumption is that the rock is isotropic. This project will model the reservoir using anisotropic permeability for Darcy’s law and a more realistic relationship (like Forchheimer’s equation) for the non-Darcy regime.

Lattice Boltzmann method for multiphase flow through porous media (Mobil Technology Company, Petroleum Research Fund, ACS-PRF# 39455-AC9)

A Lattice Boltzmann Method will be developed to describe flow through porous material in the microscopic level. Modern visualization techniques, like Magnetic Resonance Imaging or Nuclear Magnetic Resonance, can give a detailed view of the pore network in a microscopic scale. This can serve as the boundary for the application of LBM.

Model Based Simulator for high velocity flow through porous media (National Science Foundation, NSF-CMS-0084554)

In this project, we plan to develop an integrated simulator for flow through heterogeneous porous materials using a hierarchy of simulations. Current approaches involve the use of simulations having a single physical scale (see the above two projects). However, recent advances in High Performance Computing have made it possible to increase significantly the problem size. The challenge is to combine the individual simulations into an integrated multiscale system that will be able to include all physical scales and will self-adjust in accordance with the input data. Emphasis will be placed on the portability, scalability, efficiency and extensibility of the final product. The simulator will be an improved prediction tool for hydrocarbon reservoir management and will be ready for use on integrated grid architectures, as they become available.

High Performance Computation Grid Applications in Chemical Engineering

This project will combine emerging research needs in Grid computing with new research directions in engineering applications.  Specifically, this study will design, implement and deploy a Problem Solving Environment (PSE) for engineering management of complex physical systems. This Engineering Management System (EMS) will enable multiscale simulation of multiphase flow through porous media, with asynchronous, bidirectional feedback between software components, and will be applicable to a wide variety of applications by allowing plug-and-play capabilities. The specific testbed application for the PSE is the management of a hydrocarbon reservoir. Recent advances in Science Portal technology, can provide the underlying structure that such PSEs require. A cohesive, multi-university (The University of Oklahoma, University of Illinois at Urbana-Champaign, Clarkson University) research group that is focused on the use of high performance computers in chemical engineering practice has been formed to promote these ideas and to explore the possibility of funding this project.

DVP’s home |                           UPDATED: October 13, 2008