Modeling Particle Dynamics in Fluid Flow BAM Modeling
Modeling Particle Dynamics in Fluid Flow BAM Modeling Workshop April 9, 1998 F. Fan, P. Ramesh, J. Wang
Fluid particle interaction models • Very dilute suspensions: particle based models – Aerosol dynamics: Effect of particle motion on fluid flow negligible – Two-phase flow: Effect of particles motion on flow important • Less dilute suspensions: continuum-based models – Multiphase flow – Drag-limited behavior: EHD convection
Fluid-particle interactions • Force on the particles u – hydrodynamic drag: Cd(vp-u) – long range forces (q. E, mg…) vp – short range forces: particle-particle (Fp-p), particlesurface (Fp-s) • Force on the fluid: – particle drag: Cd(u-vp)
Aerosol Dynamics • Neglect effect of particle motion on fluid flow • Neglect particle-particle, particle-surface interactions • Fluid motion and particle motion are uncoupled Incompressible Navier-Stokes
Two-phase flow: particle approach • Include particle motion on fluid flow • particle-particle, particle-surface interactions may be important • Fluid motion and particle motion are coupled Two-way coupling
Multiphase flow • Continuum approximation • f-fluid phase, s-solid phase • volume fractions: ff and fs, Solid Phase Mass Momentum Fluid Phase Mass Momentum
Drag limited regime • • Inertia of the particles can be neglected (e. g. ions) particle-particle & particle surface interactions particles are in the mobility limit: us=mc. E+uf charge density rc=fsrs(q/m) EHD body force
Multiphase simulations with FLUENT • User defined subroutines for q. E force and space charge effect of fields • FLUENT multiphase model from granular flows • Lots of empirical correlations based on very little data.
Multiphase simulations with FLUENT Air flow induced by toner motion across the gap Receiver E=1 V/m 400 m Toner 25 m 400 m Donor Toner Layer: f=0. 6, q/m=25 m. C/gm
Toner volume fraction time=0 time=150 ms time=200 ms time=100 ms time=250 ms
Toner velocity vectors No Flow time=0 time=150 ms time=200 ms time=100 ms time=250 ms
Air velocity vectors No Flow time=0 time=150 ms time=200 ms time=100 ms time=250 ms
Multiphase simulations with FLUENT Toner development across a gap 10 ips Vdev Receiver 400 m Toner 20 ips Donor • Toner Layer: f=0. 6, q/m=25 m. C/gm • Space charge effects included
Toner velocity vectors No Flow time=0 time=1. 5 ms time=0. 5 ms time=2. 0 ms time=1. 0 ms time=2. 5 ms
Air velocity vectors time=0 time=1. 5 ms time=0. 5 ms time=2. 0 ms time=1. 0 ms time=2. 5 ms
Toner volume fractions Donor Receiver
- Slides: 16