1. Stratification: volume fraction gradient
PIV: shift small parts of images to find their velocities at the maximum fit, which is great if you have blur images.
2. Fig.2 indicate how stratification influcence the flucatuation. The bigger the gradient is, the quicker for denser particle groups to find the proper height for them. Many previous experiments about flucatuations didn't consider the influcence of the gradient, which turns out to be important here
3. Fig.3 : No matter what direction of the velocity, they all are affected by large gradients.
4. Sedimentation and fluidazation
Sedimentation is just letting particles settling down
Fluidization is pumping fluid up and make particles stablized.
Reviewed by
dchen
- 2008-03-27 02:10:57
The study of velocity fluctuations in the sedimentation of spheres is complicated by the time evolution of the underlying particle distribution, both at the microscale and in the bulk. We perform a series of experiments and simulations to isolate the effect of an initial, stable stratification in the particle concentration. The directly observed dependence of velocity fluctuations on stratification agrees with a previously obtained scaling theory
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