Time Response of Flow Resistance in Oscillating Flow of Concentrated Particle Suspensions

By making the vertical movement of the cylinder (an aluminum rod) in a pipe including a concentrated particle suspension, we provided the oscillating flow of concentrated particle suspension. We discussed the particle behavior from the change in liquid pressure measured at the pipe bottom. The test fluid is a mixture of glycerin and acrylic spherical particles, and the volume fraction of particles is 40%. In the oscillation with a short period, we found that there is difference in time response of pressure with regard to the moving directions of the aluminum rod. Especially, in the case of the pushing of the aluminum rod into the particle suspension, the abrupt increment of pressure was confirmed in the pressure curve and it suggested the occurrence of particle aggregation. Furthermore, these changes in liquid pressure were observed on the experiments of other oscillating amplitudes and were considered to relate to the magnitude of deformation rate subjected to the fluids around the rod tip.