Department of Mechanical Engineering - Turbulence Research Laboratory, Columbia University
500 West 120th Street, 127 S.W. Mudd, New York, NY 10027-6699.
Tel. +1 (212) 854-2922, Fax +1 (212) 854-2922

Columbia University
Department of Mechanical Engineering
Turbulence Research Laboratory

The Turbulence Research Lab is directed by Professor Rene Chevray. Other researchers include:

• Professor Pradip Dutta -Visiting Research Scientist
• Dr. Ahmet C. Omurtag -Visiting Research Scientist
• Albert C. Wang -Ph.D. Candidate
• Victor G. Stickel, Jr. -Ph.D. Candidate
• Cleo Lymberis -Undergraduate Researcher
• Americo G. Cottely -Undergraduate Researcher

Current research interests include:

• Dynamical Systems in Fluid Mechanics and Chaotic Advection: A novel method of fluid mixing "chaotic advection" is studied from a fundamental point of view. Applications to systems which cannot sustain high strain rates are studied; in particular, this method is presently used to separate fetal erythrocytes from maternal blood (image of experimental apparatus). It is also used to separate particles with only slight variations in size or density.
  Computational Video - to play select and hold down function key F5
• initial condition - 300 particles in a "blob" - stirred for 10 cycles
• initial condition - 500 particles in a circle - stirred for 10 cycles
• initial condition - 400 particles in a line - stirred for 10 cycles

• Development of a New Model of Turbulence: An apparent body force hypothesis is put forward for turbulent flows. Important characteristics of this model include accurate prediction of complicated turbulent shear flows, in particular for zones of null velocity gradients where the shear stress is finite. A basic turbulent situation, that of a distorted duct in which a grid generated turbulence is subjected to a pure plane strain is studied experimentally to study this new model. This reorientation of the principal axes provides an example of the evolution of the principal axes of the Reynold's stress tensor in a shear flow.

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• Coating Processes with Viscoelastic Liquids: We are studying, numerically and experimentally, flows of small scale laminar free-surface flows in order to be able to deposit one or several liquid films on a moving substrate. These flows invariably involve non-Newtonian viscoelastic fluids whose behavior is little understood especially in the high Weisenberg number regime corresponding to the elastic behavior used in coating operations.

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• Drag Reduction by Polymeric Fluid: The well-known phenomenon of drag reduction by long chain molecules introduced in a turbulent flow is still not understood. In an effort to understand this mechanism, we are studying flows of polymeric fluids in a free jet configuration where the total absence of walls might reveal details of the fine structure of turbulence which is quite different with and without polymers (image of experimental apparatus).

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more images

• Stability Analysis of Free Surface Flows: A numerical method to treat two-dimensional incompressible fluid flows with free surfaces has been developed. This scheme has also been successfully applied to the linearized perturbed Navier-Stokes equation in order to predict three-dimensional instabilities of flows with and without free surfaces. Several simulations have been performed on problems such as; the well-known Taylor instability of flows between two cylinders and flows with free surface instability found in coating processes. Verification of experimental results has been acheived via flow visualizations using streakline photography.

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last modified- 9/18/96