New directions in turbulence experlments


  • Amador Muriel Center for Fluid Dynamics, University of the Philippines Los Baños


In the past five years, a systematic development of a microscopic theory of turbulence has been presented by researchers from NIP−UP Diliman, the Center for Fluid Dynamics−UPLB, Stanford University, and the Institute of Thermophysics of the Siberian Branch of the Russian Academy of Science. From early predictions by Muriel and Dresden, it was suggested that the critical fluid velocity at which turbulence begins is dependent on molecular properties, specifically internal degrees of freedom like molecular rotation. This prediction is in harmony with a quantum interpretation for the onset of turbulence. There now exists experimental observations that the critical velocity, and the critical Reynolds number, are different (by about 9%) for carbon monoxide and nitrogen, two gases of identical physical parameters. This is in marked departure from classical expectations, where the assumption is that the critical Reynolds number is the same regardless of the fluid.
A conservative interpretation of these results is that more experiments need to be done, to make both our predictions and experimental confirmations more universally acceptable. In this talk, we will present the experimental results to date, and describe the apparatus, with the view of encouraging Filipino physicists to organize and join the other teams working on the problem. The apparatus used to date will be described, with local procurement in mind. Improvements in the experimental techniques will be discussed.
Several other predictions and possible experiments will be discussed, including: (a) the excitation of laminar flow into turbulence by a laser field of the right frequency, (b) the dependence of the critical velocity, or Reynolds number on a large external field in a fluid with large polarizability, (c) the detection of radiation emanating from fully developed turbulence. These experiments, suggested by our microscopic theory of turbulence, might conceivably start a new direction in turbulence research that makes use of molecular spectroscopy, atomic and molecular physics. If most of our predictions are verified, there will be some fundamental changes in the theory of turbulence, one that would make use of molecular structure, hence quantum mechanics, answering the question once posed by George Uhlenbeck, "Wherein hydrodynamics is Planck's constant?" We believe that we have found in turbulence, a 100-year old problem.




How to Cite

A Muriel, New directions in turbulence experlments, Proceedings of the Samahang Pisika ng Pilipinas 15, SPP-1997-TP-01 (1997). URL: