 |
|
|
| Lance R. Collins |
S.C. Thomas Sze Director
Mechanical and Aerospace Engineering |
|
| Research Group Web Page:
| Fluid Dynamics Research Group
|
| Address: |
105 Upson Hall
Cornell University
Ithaca, NY 14853 |
![]() |
Phone:
Fax:
E-mail: |
(607) 255-0379
(607) 255-1222
LC246@cornell.edu |
|
|
Professor Collins is interested in turbulence physics, direct numerical simulations, spectral modeling, and probability density function modeling. Areas of interest include: cloud physics; aerosol transport, clustering and high-speed particle tracking; premixed and non-premixed combustion; scalar mixing modeling with/without chemical reaction; polymer drag reduction; fundamental study of homogeneous turbulent shear flow; and high-performance computing. |
| Current Projects |
- Aerosol Clustering in Turbulence: This is an investigation of particle clustering in turbulent flows using a combination of direct numerical simulation and holographic particle imaging (performed by Professor Hui Meng's group in the MAE department of SUNY-Buffalo). The goal is to perform state-of-the-art high-resolution simulations (with up to 2048 cubed grid points and tens of millions of particles) to study the scaling of particle clustering with Reynolds number. The main application of this work is to understanding the effect of atmospheric turbulence on cloud formation. Despite decades of research there are number of open questions concerning how clouds develop. These questions take on particular significance in global climate models, where cloud cover can act to mitigate the greenhouse gas effect. Holographic imaging performed by my collaborator will enable three-dimensional measurements of up to 100,000 particles in a turbulent flow. The ultimate goal of this project is to bring together experiment and simulation under conditions of nearly perfect geometric and parameteric overlap. (Sponsor: NASA microgravity fluid physics)
- High-Speed Particle Tracking: The goal of this project is to develop an instrument capable of tracking several hundred particles embedded in a turbulent flow for long times (integral times) with high accuracy (sub-Kolmogorov time resolution) for the purpose of analyzing particle accelerations and multi-particle dynamics in turbulence. Cameras must be capable of 100,000 frames per second in order to make this feasible. In addition to the challenge with speed, the need for spatial accuracy requires four cameras to image a single volume. Commercial cameras are being mounted to a von Karman turbulence device in Professor Bodenschatz laboratory (Physics, Cornell) and a wind tunnel in the laboratory of Professor Warhaft (MAE, Cornell). Our role is to provide direct numerical simulation data to assist in developing the image processing software required to obtain the particle trajectories from the camera images. (Sponsor: NSF Major Research Instrumentation Award)
- Polymer Drag Reduction: It's been known for some time that the addition of trace amounts of polymer in a Newtonian solvent (parts per million by weight) can reduce the drag on a stationary surface by as much as 80%. Nevertheless, our understanding of the mechanism is not sufficient for use of this technology in ships and submarines. Recent advances in the representation of the non-Newtonian effects of the polymer have enabled numerical simulation of drag reduction for the first time. The goal of this project is to exploit simulations to develop models capable of describing drag reduction around complex flows such as the flow around the hull of a ship. This project involves a collaboration with a number of scientists at other institutions with complementary expertise. Our role is to continue development of direct numerical simulations of polymer solutions for isotropic turbulence and homogeneous turbulent shear flow. (Sponsor: DARPA Friction Drag Reduction Program)
- Scalable Combustion Algorithms: This project involves an interdisciplinary team of investigators, including collaborators from industry and national laboratories, who will work together to develop portable computational modules that will describe various aspects of turbulence, chemical reaction and radiation transport in nonpremixed flames. The unique nature of each of these processes requires specialized algorithms that must be integrated to accomplish the overall goal. Our component of this project will be the development of improved models for mixing within the probability density function framework. Several direct numerical simulations of flames (incorporating radiation transport through a novel Monte Carlo technique) will be done to aid in the development of the model. (Sponsor: NSF Information Technology Research)
|
| Selected Publications |
|
Brucker, K. A., Vaithianathan, T. and L. R. Collins
"Efficient algorithm for simulating homogeneous turbulent shear flow without remeshing," J. Comp. Phys., in preparation. |
|
Chun, J., Koch, D. L., Rani, S., Ahluwalia, A. and L. R. Collins
"Clustering of aerosol particles in isotropic turbulence," J. Fluid Mech., accepted for publication. |
|
Keswani, A. and L. R. Collins
"Reynolds number scaling of particle clustering in turbulent aerosols," New J. Physics 6:119 (2004). |
|
Cristini, V., Blawzdziewicz, J., Loewenberg, M. and L. R. Collins
"Breakup in stochastic Stokes flows: sub-Kolmogorov drops in isotropic turbulence," J. Fluid Mech. 492:231-250 (2003). |
|
Moody, E. G. and L. R. Collins
"Effect of mixing on the nucleation and growth of titania particles," Aerosol Sci. Tech. 37:403-424 (2003). |
|
Vaithianathan, T. and L. R. Collins
"Numerical approach to simulating turbulent flow of a viscoelastic polymer solution," J. Comp. Phys. 187:1-21 (2003). | |
| Biography |
|
Professor Collins joined the Sibley School of Mechanical & Aerospace Engineering at Cornell University in the Spring semester of 2002 following eleven years as Assistant Professor, Associate Professor and Professor of Chemical Engineering at The Pennsylvania State University. Since 1999, Professor Collins also held a joint appointment in the Mechanical & Nuclear Engineering Department at Penn State. In 1998 during a sabbatical leave, Professor Collins was a Visiting Scientist at the Laboratoire de Combustion et Systemes Reactifs (a CNRS laboratory in Orleans, FRANCE) and at Los Alamos National Laboratory (Theoretical Fluid Dynamics Group). Professor Collins' research combines simulation and theory to study a variety of turbulent flow processes. His work on mechanisms of droplet breakup in turbulence was recognized with the 1997 Best Paper Award from the American Institute of Chemical Engineers. He currently serves on the editorial board of the International Journal of Multiphase Flow. |
| Education |
| Ph.D. 1987 |
- |
University of Pennsylvania |
| M.S. 1983 |
- |
University of Pennsylvania |
| B.S.E. 1981 |
- |
Princeton University | | |
|
|
|
|
|
|
|
