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Particle deposition in turbulent pipe flow

Particle deposition in turbulent pipe flow. John Young & Angus Leeming Whittle Laboratory, University of Cambridge,UK A brief summary by Pavan K Kancherlapalli . Motivation.

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Particle deposition in turbulent pipe flow

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  1. Particle deposition in turbulent pipe flow John Young & Angus Leeming Whittle Laboratory, University of Cambridge,UK A brief summary by Pavan K Kancherlapalli

  2. Motivation • Particle deposition in HVAC system degrades the performance. • Inhalation • Small scale electronics • Deposition of naphthalene, sand and wax in oil pipe lines

  3. Driving forces for particle transport • Turbulent diffusion • Turbophoresis • Inertia

  4. PARTICLE TRANSPORT TO THE WALL Diffusional deposition regime: Turbulent diffusion in core and Brownian near wall Diffusion impaction regime: Gradient diffusion to stop-distance and by inertia Inertia-moderated regime: Momentum from large eddies.

  5. PARTICLE EQUATIONS OF MOTION Conservation of mass Conservation of momentum Total mass flux

  6. Reynolds Averaged Equations in cylindrical coordinates For fully developed flow Axial variation of product of fluctuating components is assumed zero

  7. Final form of convective equation Turbulence Modeling Where

  8. Boundary condition for convective equations: Boundary condition for mass conservation equation: At centerline and at wall when convection dominates at wall when Brownian dominates Final form of particle equations for fully developed flow

  9. Solution of particle equation • Forward time and central space finite difference • Different grid for momentum and mass equation • Geometric progression of grid spacing

  10. Effect of Turbophoresis

  11. Comparison of r.m.s fluctuating velocity of particles with DNS results

  12. Conclusions • Mathematical description of particle transport is done. • Modeling agrees well with DNS data. • Velocities and particle densities at wall were obtained. • Memory effect of large particles has been neglected. • Wall effects have been neglected.

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