Full Record

Author | Ben Dhia, Zakaria |

Title | Novel Treatments for Multi-phase Flow Prediction Inspired By Kinetic Theory |

URL | http://hdl.handle.net/10393/34924 |

Publication Date | 2016 |

Date Accessioned | 2016-06-22 11:28:41 |

University/Publisher | University of Ottawa |

Abstract | This study entails an investigation of a novel moment closure, originally constructed for rarefied-gas prediction, to the modelling of inert, dilute, disperse, particle flows. Such flows are important in many engineering situations. As one example, in internal-combustion engines, fuel is often injected as a spray of tiny droplets and, during combustion, a cloud of tiny soot particles can be formed. These particle phases are often difficult to model, especially when particles display a range of velocities at each location in space. Lagrangian methods are often too costly and many Eulerian field-based methods suffer from model deficiencies and mathematical artifacts. Often, Eulerian formulations assume that all particles at a location and time have the same velocity. This assumption leads to nonphysical results, including an inability to predict particle paths crossing and a limited number of boundary conditions that can be applied. The typical multi-phase situation of many particles is, in many ways, similar to that of a gas compressed of a huge number of atoms or molecules. It is therefore expected that powerful techniques from the kinetic theory of gases could be applied. This work explores the advantages of using a modern fourteen-moment model, originally derived for rarefied gases, to predict multi-phase flows. Details regarding the derivation, the mathematical structure, and physical behaviour of the resulting model are explained. Finally, a numerical implementation is presented and results for several flow problems that are designed to demonstrate the fundamental behaviour of the models are presented. Comparisons are made with other classical models. |

Subjects/Keywords | Multi-phase Flow; Kinetic Theory |

Language | en |

Country of Publication | ca |

Record ID | handle:10393/34924 |

Repository | ottawa |

Date Indexed | 2018-01-03 |

Issued Date | 2016-01-01 00:00:00 |

Sample Search Hits | Sample Images | Cited Works

…*phase*
*flow* occurring in the engine is necessary.
*Multi*-*phase* flows are omnipresent in numerous practical engineering situations. They
are defined as the concurrent *flow* of materials with diverse states or phases (i.e., gas, solid,
or liquid)…

…models
Continuous distribution models
Euler
Sachdev
Gaussian
14 Moment
Figure 1.1: Hierarchy of models for *multi*-*phase* *flow* prediction
2
DQMOM
to model *multi*-*phase* *flow*. We start with the Lagrangian treatment. In this treatment, we
track the…

…solutions using a direct particle simulation.
Previous studies have had some success in applying techniques from kinetic theory to
*multi*-*phase* *flow* prediction. One technique allows particles at a location to have one of a
set of possible velocities. This can…

…compressible Euler equations to the particle
4
*phase*. This technique is commonly used and available in many *multi*-*phase* *flow* solvers.
Another model, originally derived by Levermore and Morokoff [2, 1, 18], admits 10 equations. The 10-moment…

…to be bi-model. It is expected that
this will greatly improve the accuracy of the predictions for *multi*-*phase* *flow*. Up to now,
this model has only been applied to pure gas *flow*. This work represents its first application
to *multi*-*phase* *flow* prediction…

…discussed.
In Chapter 4, we review the new fourteen-moment model [21] that was proposed for gas
*flow* prediction and show how it is modified to model *multi*-*phase* *flow*. In Chapter 5, a
numerical method for the solution of the resulting governing…

…models.
7
Chapter 2
Overview of *Multi*-*Phase* Flows and
Gaskinetic Theory
2.1
*Multi*-*Phase* *Flow*
The behaviours of *multi*-*phase* gas-particle flows can be characterized through the definition
of the Stokes number, St, for a particle in a background *flow*…

…particle *phase* and the background *phase*. For Stokes *flow*, it can be expressed
8
Table 2.1: Definition of several *multi*-*phase* *flow* regimes
St 1 Particle velocity is nearly the same as the fluid velocity
St ≈ 1
Significant velocity difference are present…