Deposition of wet microparticles on a fiber: Effects of impact velocity and initial spin

Abstract

Inertial deposition of wet microparticles on a fiber is numerically investigated by means of discrete element method, taking the effects of impact velocity and initial spin into consideration. Results indicate that the overall, normal and tangential coefficients of restitution remain zero as the impact velocity is lower than a critical value, beyond which these restitution coefficients will increase nonlinearly with increasing the impact velocity. As the impact angle increases, the normal critical impact velocity will show a parabolic decrease and the tangential critical impact velocity will increase linearly, different from dry collisions where the critical impact velocities almost keep constant. As the impact velocity increases, the capture efficiency of wet microparticles by the fiber decreases exponentially, meanwhile the deposit microstructures tend to be denser. It becomes much more complex if clockwise or anti-clockwise initial spins are encountered. The rotational coefficient of restitution will first decrease with increasing the rotational rate until reaching a minimum value, beyond which the rotational restitution coefficient will increase as the rotational rate increases further. However, the overall restitution coefficient changes slightly if the rotational rate is less than about 105 rad/s. The effect of clockwise spin on capture efficiency is found to be distinctly different from that of anti-clockwise spin, and it can be reasonably interpreted by their effects on the overall coefficient of restitution.