This thesis presents a study of reduced-order models based on proper orthogonal
decomposition applied to non-isothermal transport phenomena in °uidized beds. A
numerical °ow solver called Multiphase Flow with Interphase eXchanges (MFIX) was
used to generate a database of solution snapshots for proper orthogonal decomposi-
tion (POD). Using POD, time independent basis functions were extracted from the
data and the governing equations of the numerical solver were projected onto the basis
functions to generate reduced-order models. A reduced-order model was constructed
that simulates multi-phase isothermal and non-isothermal °ow. In the reduced-order
models (ROMs) the large number of partial di®erential equations were replaced by a
much smaller number of ordinary di®erential equations. These reduced-order models
were applied to two reference cases, a time extrapolation case and a time-dependent
period boundary condition case. Three additional acceleration techniques were devel-
oped to further improve computational e±ciency of the POD based ROM: 1) Database
splitting, 2) Freezing the matrix of the linear system and 3) Time step adjustment.
Detailed numerical analysis of both the full-order model, MFIX and the POD-based
ROM, including estimating the number of operations and the CPU time per iteration,
was performed as part of this study. The results of this investigation show that the
reduced-order models are capable of producing qualitatively accurate results with less than 5% error with a two-order of magnitude reduction of computational costs.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-2623 |
| Date | 15 May 2009 |
| Creators | Richardson, Brian Ross |
| Contributors | Cizmas, Paul |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | electronic, application/pdf, born digital |
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