A4 Conference proceedings

Assessing the failure of continuum formula for solid-solid drag force using discrete element method in large size ratios


Open Access publication

Publication Details
Authors: Jalali Payman, Hyppänen Timo
Publisher: EDP Sciences: EPJ Open Access / EDP Sciences
Publication year: 2017
Language: English
Related Journal or Series Information: EPJ Web of Conferences
Title of parent publication: EPJ Web of Conferences
Volume number: 140
Start page: 1
End page: 4
Number of pages: 4
ISSN: 2101-6275
eISSN: 2100-014X
JUFO-Level of this publication: 1
Open Access: Open Access publication

Abstract

In loose or moderately-dense particle mixtures, the contact forces between particles due to successive collisions create average volumetric solid-solid drag force between different granular phases (of different particle sizes). The derivation of the mathematical formula for this drag force is based on the homogeneity of mixture within the calculational control volume. This assumption especially fails when the size ratio of particles grows to a large value of 10 or greater. The size-driven inhomogeneity is responsible to the deviation of intergranular force from the continuum formula. In this paper, we have implemented discrete element method (DEM) simulations to obtain the volumetric mean force exchanged between the granular phases with the size ratios greater than 10. First, the force is calculated directly from DEM averaged over a proper time window. Second, the continuum formula is applied to calculate the drag forces using the DEM quantities. We have shown the two volumetric forces are in good agreement as long as the homogeneity condition is maintained. However, the relative motion of larger particles in a cloud of finer particles imposes the inhomogeneous distribution of finer particles around the larger ones. We have presented correction factors to the volumetric force from continuum formula.


Last updated on 2018-19-10 at 07:55