Comparison of Backwash Models for Granular Media

Abstract

This work composes a general semiempirical formula of fluidization and theoretical and experimental models developed by the writers. Both mathematical approaches adopt unisize granular grains, but of different origins. The former relies on the assessment of the hydraulic flow conditions prevailing at the time of the tests, which incorporate values of both Reynolds number and n and lead to a value of n1. The last three values are dependent on the defined mean value of the designated diameter. The later mathematical and experimental models account for all kinds and types of flow conditions, independent of any other mathematical relationships, and only consider the mean hydraulic diameter of the unisized grains. The other main section deals with the effect of the initial volumetric concentration of fluidized uniform particles or initial fixed bed porosities under the state of expansion or contraction of the fluidization determined by experiment.