G. Paul Neitzel
Professor and Associate Chair for Graduate Studies
| Office: | Love, Room 229 |
| Phone: | 404.894.3242 |
| Fax: | 404.894.8496 |
| E-mail: | |
Education
- Ph.D., The Johns Hopkins University, 1979
- M.S., The Johns Hopkins University, 1974
- B.S., Rollins College, 1969
Research Areas and Descriptors
Background
Dr. Neitzel's research is in the area of fluid mechanics. His doctoral work was of a theoretical and numerical nature, studying the hydrodynamic instability of the problem called spin-down. He continued to work on the hydrodynamic stability of unsteady flows for several years and still maintains an interest in this area. In the mid-1980s, he began to conduct research on flows related to materials processing applications such as crystal growth from bulk melts. Such flows are strongly influenced by the phenomenon known as thermocapillarity, which is the variation of a liquid's surface tension with temperature. The instability of a type of convection driven by this is known to cause the appearance of dopant striations in silicon grown by the so-called "float-zone" crystal-growth process. Dr. Neitzel, his colleagues, and students have computed domains of stable and unstable flow in a model system and have also demonstrated, experimentally, how it may be possible to suppress the flow oscillations which lead to the above striations. Much of the work done by Dr. Neitzel since receiving his Ph.D. has been of an experimental nature; currently, experimental research makes up more than half of his current projects. He began at Tech in 1990 as a Professor. Prior, he was Assistant, Associate, and Professor at Arizona State University.
Research
Dr. Neitzel's current research interests are in a couple of areas: free-surface flows involving droplets and surfaces; and bioreactor fluid dynamics. Permanent noncoalescence of droplets of the same liquid and permanent nonwetting of a solid surface by a normally wetting liquid are subjects that were stumbled upon in space-flight experiments involving liquid bridges. Temporary noncoalescence and nonwetting events have been observed by others such as Lord Rayleigh as far back as the turn of the twentieth century. Thermocapillarity is one means by which two surfaces of the same liquid or those of a liquid and solid can be forced to remain apart. Such work has potential applications in microgravity environments as low-friction bearings and in lab-on-a-chip devices.
Dr. Neitzel and his students have demonstrated how permanent nonwetting can be exploited to optically levitate droplets above solid surfaces and to transport them from point to point. Other droplet-surface flows of interest are those associated with droplet impact on solid surfaces. One application of such work is to so-called “blood-spatter” analysis at crime scenes. In the area of bioreactor fluid dynamics, Dr. Neitzel’s research is concerned with bioreactors used for mammalian-tissue engineering. It is known that certain tissues, such as cartilage, exhibit “mechano-transduction,” in that they respond physiologically to their mechanical environment, including the complex flow environments found in some bioreactor systems. His group is involved with the measurement of the flow fields in these bioreactors and, through collaboration with others who are simulating these flow fields and growing tissues in controlled, low-shear environments as well as in the bioreactor, to constructing a mathematical model of tissue growth.
Dr. Neitzel’s research has been funded through grants from the National Aeronautics and Space Administration, the National Science Foundation, the Office of Naval Research, and the Air Force Office of Scientific Research.
Distinctions
- National Aeronautics and Space Administration
- On-Orbit Evaluation Board (International Space Station), 2000-2007
- Office of Biological and Physical Research Physical Sciences Advisory Subcommittee, 1997-2006
- Fluid Physics Discipline Working Group Chair, 1997-2002
- Space Station Utilization Advisory Subcommittee Member, 1995-1999
- American Society of Mechanical Engineers Fellow, 2001
- Morehouse School of Medicine Space Medicine and Life Sciences Research Center External Advisory Board, 2000-2007
- American Physical Society Fellow, 1994
- American Institute of Aeronautics and Astronautics Associate Fellow, 1990
- Alexander von Humboldt Foundation of Germany Research Fellowship, 1985
- National Science Foundation Presidential Young Investigator Award, 1984-1989
Representative Publications
- R. M. MacMeccan et al. 2009. Simulating Deformable-particle Suspensions Using a Coupled Lattice-Boltzmann and Finite-Element Method. Journal of Fluid Mechanics 618, 13-39.
- P. T. Nagy and G. P. Neitzel. 2008. Optical Levitation and Transport of Microdroplets: Proof of Concept. Physics of Fluids 20, 101703-1-4.
- C.-W. Kuo, J.-C. Chen and G. P. Neitzel 2007. Numerical Simulation of Isothermal Nonwetting. International Journal for Numerical Methods in Fluids 53, 257-275.
- J.-C. Chen, C.-W. Kuo, and G. P. Neitzel. 2006. Numerical Simulation of Thermocapillary Nonwetting. International Journal of Heat and Mass Transfer 49, 4567-4576
- M. K. Smith and G. P. Neitzel. 2006. Multiscale Modeling in the Numerical Computation of Isothermal Nonwetting. Journal of Fluid Mechanics 554, 67-84.
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