Comparison of Kinetic Liquid Bridge Force Models in DEM

In many powder handling processes, liquid is added and dispersed into bulk dry powder. Some examples include agglomeration, coating, mixing and catalytic reactions. To model these systems, simulations of wet particles with small amounts of liquid are often performed by incorporating liquid bridge forces consisting of static (capillary) and kinetic (lubrication and viscous) forces into Discrete Element Method (DEM) [1]. While most of such work have focussed on static or capillary force dominant systems, i.e. the capillary number is small, (typically using water or low viscosity liquids), fewer work have investigated kinetic force dominant systems.

The kinetic force models are generally derived from the Reynolds lubrication theory [e.g. 2-3]. Recently, we proposed an improved kinetic force model via Direct Numerical Simulations (DNS) of a liquid bridge formed between two relatively moving particles [4]. In this work, we investigated and compared the kinetic force model with other models in literature from DEM case studies of wet particle flow, particularly for high viscosity liquids where the kinetic force is dominant.

[1] G. Lian, C. Thornton, M.J. Adams, Discrete particle simulation of agglomerate impact coalescence, Chemical Engineering Science, 53 (1998) 3381-3391.

[2] M.J. Adams, V. Perchard, The cohesive forces between particles with interstitial liquid, Institute of Chemical Engineering Symposium, (1985) 147-160.

[3] A. Goldman, R. Cox, H. Brenner, Slow viscous motion of a sphere parallel to a plane wall—I Motion through a quiescent fluid, Chemical Engineering Science, 22 (1967) 637-651.

[4] K. Washino, E.L. Chan, T. Matsumoto, S. Hashino, T. Tsuji, T. Tanaka, Normal viscous force of pendular liquid bridge between two relatively moving particles, Journal of Colloid and Interface Science, 494 (2017) 255-265.