A regularized deconvolution method for large-eddy simulations of multiphase reacting flows
Abstract/Contents
- Abstract
- In Large-eddy simulations (LES) for turbulent multiphase and reacting flows, sub-grid scale (SGS) models are required to represent the interaction between turbulence, combustion, and the dispersed phase. Different approaches have been proposed in the literature to represent these unresolved terms, such as gradient diffusion models for turbulent scalar fluxes, presumed-PDF and artificially thickened flame models for turbulence-chemistry interactions, and random walk and stochastic Langevin models for turbulence-spray interactions. Although these modeling approaches show good performance in application to a wide range of problems, it is also observed that different combinations of models lead to different results for the same simulation configuration, and the performance of these models depends highly on flow and flame configurations. This model behavior is a consequence of the inconsistency between closure models and LES formulations. To address this inconsistency, closure models in coherence with the LES formulation need to be developed. In this work, a regularized deconvolution method (RDM) for the SGS closure models is developed. This method is based on an approximate inversion of the filtering operation in LES, which is consistent with the LES formulation. The method is formulated as an optimization problem. To ensure the properties of boundedness and conservation for reactive scalars, which are not considered in existing deconvolution methods, constraints are introduced in the formulation of RDM. The framework of RDM is developed in the context of both explicitly and implicitly filtered LES. For explicitly-filtered LES, RDM reconstructs the flow structures that are under-resolved. In this context, the deconvolution is formulated as a solution to a Wiener filtering. To account for the boundedness and conservation of reactive scalars, a constrained minimum mean square error problem is solved on a subset of the deconvolution solution that violates these properties. In an implicitly-filtered LES, the unresolved flow structures require modeling. To provide a correct description of these sub-grid fluctuations, an additional constraint is enforced in the RDM framework to regularize the sub-grid scale energy. The performance of RDM is examined for the closure of turbulence-flame interaction, turbulent scalar transport, and sub-grid dispersion through both \emph{a priori} and \emph{a posteriori} analysis of multiple LES configurations. Improved predictability is observed with RDM compared to other SGS closures model combinations.
Description
| Type of resource | text |
|---|---|
| Form | electronic resource; remote; computer; online resource |
| Extent | 1 online resource. |
| Place | California |
| Place | [Stanford, California] |
| Publisher | [Stanford University] |
| Copyright date | 2018; ©2018 |
| Publication date | 2018; 2018 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Wang, Qing |
|---|---|
| Degree supervisor | Ihme, Matthias |
| Thesis advisor | Ihme, Matthias |
| Thesis advisor | Lele, Sanjiva K. (Sanjiva Keshava), 1958- |
| Thesis advisor | Moin, Parviz |
| Degree committee member | Lele, Sanjiva K. (Sanjiva Keshava), 1958- |
| Degree committee member | Moin, Parviz |
| Associated with | Stanford University, Department of Mechanical Engineering. |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Qing Wang. |
|---|---|
| Note | Submitted to the Department of Mechanical Engineering. |
| Thesis | Thesis Ph.D. Stanford University 2018. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2018 by Qing Wang
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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