Oscillating fluid

The theory explains why a succession of shocks may occur in BLEVEs. A first shock is produced by the escape of vapor, a second by evaporating liquid, a third by the second shock of the oscillating fluid bubble, and possible additional shocks produced by combustion of released fluid. It is also possible for these shocks to overlap each other, especially at greater distances from the explosion. 

Levitation is a stable condition in which a particle responds to the oscillating fluid in such a way that the influence of finite buoyancy, or gravity, forces is completely neutralized so that the particle oscillates about a fixed position (Houghton, 1963, 1964, 1966, 1968 Krantz, Carley and Al-taweel, 1973 Tunstall and Houghton, 1968 Van Oeveren and Houghton, 1971). Figure 37 (Liu, 1983) shows the levitation of solid particles in air under oscillation caused by a sonic generator located at the bottom of the column. 

Both Fig. 37 and Fig. 39 show solid particles highly dispersed as a dilute phase in the oscillating fluid, either gas or liquid, without evidence of any bubbles. When a packed bed of solid particles was subjected to the action of an oscillating liquid, however, only the upstroke portion of the periodic fluid motion was capable of dispersing the solid particles against the action of gravity, while during downstroke they fell back onto the distributor plate. 

Houghton, G., Particle Trajectories and Terminal Velocities in Vertically Oscillating Fluids, Can. J. Chem. Eng., 44 90-95 (1966)... 

Houghton, G., Velocity Retardation of Particles in Oscillating Fluids, Chem. Eng. Sci., 23 287-288 (1968)... 

Amplitude Ratio and Phase Shift for Spheres Entrained in Oscillating Fluids at Low Reynolds Number... 

Fig. 11.15 Amplitude ratio and phase shift for particles entrained in oscillating fluids at low Re. (Note change to logarithmic scale at Tq — 1.)...

Figure 11.16 shows IFr as a function of N, calculated from Eq. (11-58) for various values of N. Chan et al. (C3) extended this approach to a sphere in a horizontally oscillating fluid. 

Fig. 11.16 Ratio of mean terminal velocity to terminal velocity in absence of oscillations for particles in sinusoidally oscillating fluids. Unbroken lines are predictions from Eq. (11-58) broken lines are numerical predictions (M8) for 2 mm spheres in water with y = 2.5 and values as follows curve A-0.28 B -0.42 C—0.56 D -1.11 E -1.67.

Levitation is defined as a stable condition in which a particle responds to vertically oscillating fluid so that net gravity forces are completely neutralized and the particle merely oscillates about a fixed position (H12). In terms of the preceding analysis, this means 14 = 0 (cf. Fig. 11.16). Contrary to the predictions of the numerical solutions, Feinman (FI) found that levitation can be caused by sinusoidal oscillations. Equation (11-58) predicts that 14 becomes zero if ... 

Edlich M, Yellowey CE, Jacobs CR, Donahue HJ. Oscillating fluid flow regulates cytosolic calcium concentration in bovine articular chondroctes. J Biomech. 2001 34 59-65. 

Even the incompressible fluid can also give rise to Eulerian streaming flow when a solid obstacle is in contact with the oscillating fluid. Consider a two-dimensional incompressible flow around a solid body governed by the following dimensionless equations ... 

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