Effect of electrostatic forces on the dispersion of like-charged solid particles transported by homogeneous isotropic turbulence

Abstract

The effect of electrostatic forces on the dispersion of small like-charged inertial particles transported by a homogeneous isotropic turbulent flow is analysed by means of direct numerical simulations coupled with the Lagrangian tracking of charged particles. The results show that particle dispersion decreases for increasing charge. Since turbulent particle dispersion is related to the intensity of particle agitation and to the Lagrangian particle integral time scale, we analyse the effects of electrostatic forces on these two quantities. Particle agitation decreases for increasing particle charge. In fact, particle kinetic energy is not directly modified by electrostatic forces, which are conservative, it is rather the particle entrainment by fluid turbulence that is modified. To support this claim, one shows that the fluid–particle velocity covariance is destructed by electrostatic forces, a destruction can be predicted by drawing an analogy between inter-particle collisions and Coulomb collisions. As expected, electrostatic forces decorrelate particle velocities leading to a decrease of the Lagrangian particle integral time scale. Finally, one shows that the analogy with inter-particle collisions allows us to predict the reduction of particle dispersion.

Unveiling the spectrum of electrohydrodynamic turbulence in dust storms

“…As reported in Ref. 38 , the electrostatic effects on particle dynamics are negligible when S t el ≪ 1, while they are dominant when S t el ≫ 1.…”

“…Meanwhile, four key particle parameters are presented in Table 2 . Here, particle-to-air mass loading ratio Φ m 35 , 36 , Stokes number S t 37 , electrostatic Stokes number S t e l 38 , and the ratio of the vertical terminal settling velocity of dust particles to the typical Lagrangian vertical air velocity w t /( κ u τ ) 39 , are used to quantify the importance of particle-turbulence coupling, particle inertia, electrostatic force, and gravitational settling, respectively.…”

“…Second, the effects of electrostatic force on the dust particles can be quantified by the electrostatic Stokes number S t el , which is defined as 38 …”

Charge–velocity correlation transport equations in gas–solid flow with triboelectric effects

“…The effect of short-range electric interaction forces on the particle dynamics has been studied in very dilute turbulent flows (see e.g. Boutsikakis, Fede & Simonin 2022), but is generally completely neglected in dense flows and should be the subject of future studies using computational fluid dynamics/discrete element method (CFD/DEM) (Kolehmainen et al. 2016).…”

“…The effect of short-range electric interaction forces on the particle dynamics has been studied in very dilute turbulent flows (see e.g. Boutsikakis, Fede & Simonin 2022), but is generally completely neglected in dense flows and should be the subject of future studies using computational fluid dynamics/discrete element method (CFD/DEM) (Kolehmainen et al 2016). On the other hand, the short-range electrical interaction between particles has a very important effect on the charge exchange between colliding particles and it is taken into account using the electrical collision model presented in the next section.…”