Accurate buoyancy and drag force models to predict particle segregation in vibrofluidized beds
| Autor: | Mehrdad Kiani Oshtorjani, Liu Meng, Christoph R. Müller |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Convection
Buoyancy Vibro-fluidized Bed Intruder engineering.material Segregation Granular Buoyancy Force Granular Drag 01 natural sciences 010305 fluids & plasmas Physics::Fluid Dynamics 0103 physical sciences discrete element 010306 general physics convection laws Physics granular segregation Mechanics Critical value Vibration Lift (force) Spring (device) Drag engineering Granularity driven segregation size segregation |
| Zdroj: | Physical Review E, 103 (6) |
| ISSN: | 1539-3755 1063-651X 1095-3787 1550-2376 |
| Popis: | The segregation of large intruders in an agitated granular system is of high practical relevance, yet the accurate modeling of the segregation (lift) force is challenging as a general formulation of a granular equivalent of a buoyancy force remains elusive. Here, we critically assess the validity of a granular buoyancy model using a generalization of the Archimedean formulation that has been proposed very recently for chute flows. The first model system studied is a convection-free vibrated system, allowing us to calculate the buoyancy force through three different approaches, i.e., a generalization of the Archimedean formulation, the spring force of a virtual spring, and through the granular pressure field. The buoyancy forces obtained through these three approaches agree very well, providing strong evidence for the validity of the generalization of the Archimedean formulation of the buoyancy force which only requires an expression for the solid fraction of the intruder, hence allowing for a computationally less demanding calculation of the buoyancy force as coarse graining is avoided. In a second step, convection is introduced as a further complication to the granular system. In such a system, the lift force is composed of granular buoyancy and a drag force. Using a drag model for the slow-velocity regime, the lift force, directly measured through a virtual spring, can be predicted accurately by adding a granular drag force to the generalization of the Archimedean formulation of the granular buoyancy. The developed lift force model allows us to rationalize the dependence of the lift force on the density of the bed particles and the intruder diameter, the independence of the lift force on the intruder diameter, and the independence of the lift force on the intruder density and the vibration strength (once a critical value is exceeded). Physical Review E, 103 (6) ISSN:1539-3755 ISSN:1063-651X ISSN:1095-3787 ISSN:1550-2376 |
| Databáze: | OpenAIRE |
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