  Thus far, Computational Fluid Dynamics (CFD) simulations fail to predict the
electrostatic charging of particle-gas flows reliably. The lack of a predictive
tool leads to powder operations prone to deposits and discharges, making
chemical plants unsustainable and prime candidates for explosions. This paper
reviews the rapid progress of numerical models in recent years, their
limitations, and outlines future research. In particular, the discussion
includes CFD models for the physics and chemistry of particle electrification.
The condenser model is most popular today in CFD simulations of powder flow
electrification but fails to predict most of its features. New experiments led
to advanced models, such as the non-uniform charge model, which resolves the
local charge distribution on non-conductive particle surfaces. Further, models
relying on the surface state theory predicted bipolar charging of polydisperse
particles made of the same material. While these models were usually
implemented in CFD tools using an Eulerian-Lagrangian strategy, recently
Eulerian methods successfully described powder charging. The Eulerian framework
is computationally efficient when handling complete powders; thus, Eulerian
methods can pave the way from academic studies to application, simulating
full-scale powder processing units. Overall, even though CFD models for powder
flow charging improved, major hurdles toward a predictive tool remain.
