Nonlinear Hydrodynamic Effects Research Articles

Off-axis response for particles passing through long apertures in Coulter-type counters

A novel modification of the resistive pulse technique (Coulter principle) has been used to investigate how the measured resistance pulse amplitude depends on the off-axis particle position in long pores. By pressure drive, a particle enters a current-carrying pore and an increase in resistance proportional to the particle volume is detected. When the particle exits the pore, the pressure is reversed such that the particle re-enters the pore and the same particle can thus be studied for a long time. In Poiseuille flow, solid spheres migrate to an off-axis equilibrium position and this non-linear hydrodynamic effect has been utilised to study how the measured pulse amplitude from a single particle flowing back and forth through a pore increases when the particle migrates closer to the pore wall. The increase in pulse amplitude corresponding to a radial particle displacement from the pore axis to the wall is found to be less than 10% for all particle and pore sizes studied. This is considerably less than predicted by the off-axis upper-limit theory of Smythe.

A time domain solution for the attenuation, at high amplitudes, of perforated tube silencers and comparison with experiment

A numerical method, for determining the sound transmission loss of perforated tube silencers in the exhaust systems of internal combustion engines, is described; mean fluid flow and intense sound are allowed for in the analysis. The quasi-one-dimensional equations governing the sound field are approximated in finite difference form and are solved in the time domain. This is because non-linear hydrodynamic effects at the orifices need to be taken into account, and a time domain solution is a particularly versatile way of doing this. Transmission loss data measured on two experimental silencers are presented alongside numerical predictions and agreement is shown to be very good. Comparison is made between the present scheme and an equivalent frequency domain analysis and it is seen that the time domain method gives superior predictions of the transmission loss.

Details of phase separation processes in polymer blends

AbstractWe have investigated the details of phase separation dynamics in high‐molecular‐weight (polystyrene‐PVME) polymer blends utilizing small angle light scattering techniques and have compared our results with the various theories, computer simulations, and phase separation dynamics in small molecule systems. Although linearized theories are consistent with many qualitative features of phase separation dynamics, they fail to provide quantitative accuracy. It appears that both nonlinear terms and hydrodynamic effects must be included to provide a quantitative description. Quantitative agreement between phase separation dynamics in small molecule systems and high‐molecular‐weight polymer blends is also reported.

Secondary Flow Induced between Oscillating Circular Cylinders

The two-dimensional flow between oscillating circular cylinders is theoretically analyzed. The outer cylinder performs rotatory oscillations and the inner cylinder performs translational oscillations with small amplitude. Particular attention is focused upon a steady secondary streaming owing to the nonlinear hydrodynamic effect. The analytical expression for the secondary streaming is obtained. Streamlines of the secondary streaming are shown for a couple of values of radii of two oscillating circular cylinders. The behavior of the steady secondary streaming induced between two cylinders is clarified.

The Production of Vorticity in an Expanding, Self-Gravitating Fluid

view Abstract Citations (20) References (9) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Production of Vorticity in an Expanding, Self-Gravitating Fluid Olson, D. W. ; Sachs, R. K. Abstract A self-gravitating Newtonian perfect fluid is analyzed statistically. For homogeneous, isotropic turbulence the equations imply an expanding (or contracting) "background" model governed by the Friedmann equation. If density fluctuations are negligible and random velocity moments obey a limited joint-normal statistical assumption, then the equation for the mean-square vorticity w2 can be solved exactly, incorporating nonlinear hydrodynamic effects. For an expanding background, two qualitatively different types of solution can occur. If the background expansion eventually dominates, w2 eventually has the R -4 behavior expected from perturbation theory. But if the fragmentation of eddies dominates, the solutions for 2 blow up in a finite time. For a contracting background the solutions for w2 always blow up in a finite time. A simple physical interpretation is suggested for the formal results. Subject headings: cosmology - hydrodynamics - turbulence Publication: The Astrophysical Journal Pub Date: October 1973 DOI: 10.1086/152399 Bibcode: 1973ApJ...185...91O full text sources ADS |