Implementation of Breakup and Coalescence Models in CFD - PowerPoint PPT Presentation

1 / 14
About This Presentation
Title:

Implementation of Breakup and Coalescence Models in CFD

Description:

Implementation of Breakup and Coalescence Models in CFD Peng Chen, Chemical Reaction Engineering Laboratory Washington University St. Louis, MO 63130 – PowerPoint PPT presentation

Number of Views:99
Avg rating:3.0/5.0
Slides: 15
Provided by: Peng170
Category:

less

Transcript and Presenter's Notes

Title: Implementation of Breakup and Coalescence Models in CFD


1
Implementation of Breakup and Coalescence Models
in CFD
  • Peng Chen,
  • Chemical Reaction Engineering Laboratory
  • Washington University
  • St. Louis, MO 63130
  • CREL Group Meeting
  • December 14, 2000

2
Overview
  • Introduction
  • Bubble number density approach
  • Result
  • Future work

3
Introduction
  • The drag force term in one of the key issue of
    two-fluid model and the predictive capabilities
    of this model depend crucially on the closure.
  • Most numerical simulation resorts to single
    particle drag correlation with a mean bubble
    size. This is mostly because modeling different
    sizes of bubbles as individual phase lead to
    unrealistic computational cost and has numerical
    convergence problem.
  • However, in reality, bubble-bubble interaction
    results in local variation in bubble sizes that
    are substantially different from the mean
    bubble size assumption.
  • In order to get reasonably good simulation
    result, the mean bubble size need to be
    adjusted so that it could be far away reality.

4
Motivation
  • Bubble size distribution should be resolved
    locally by implement bubble coalescence and
    breakup into CFD framework.
  • There is rare implementation of such bubble
    breakup/coalescence model in CFD simulation of
    bubble column reactors.
  • Bubble breakup (Martínez-Bazán, 1999) and
    coalescence (Luo, 1993) model was implemented
    using bubble number density approach into FLUENT
    5.48 in the context of Algebraic Slip Mixture
    Model (ASMM).

5
Bubble Number Density Approach
  • The population balance equation for the ith
    bubble class
  • The source term may be written as

6
Closures - Breakup
  • Martínez-Bazán et al. (1999)

7
Closure - Coalescence
Luo (1993)
, ?ij di/dj,
8
  • Geometric Grid was used, xi1 2vi. x0 1mm.

Source term for particles of size xi is
9
(No Transcript)
10
Result
11
Overall 17.5 Experiment, 19.
12
Class 4 d 2.5 mm Class 6 d 4.0 mm
13
Class 12 d 16.0 mm Class 14 d 25.4 mm
14
Future Work
  • Tune up the parameters, try to got a universal
    one or some sort of correlation.
  • Test the sensitivity of boundary condition
  • Test other breakup/coalescence closure
  • Implement area transport equation approach
  • Run 3D simulation
  • Expand to Euler-Euler two fluid model
  • With optical probe data, verify the closures and
    propose own closures
Write a Comment
User Comments (0)
About PowerShow.com