Jouvray, Alexandre (2003) Computation and measurements of flows in rooms. PhD thesis, University of Warwick.

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Abstract

This thesis contributes to the numerical modelling of flows in ventilated rooms. A range
of advanced turbulence models (non-linear low Reynolds number Reynolds Averaged
Navier-Stokes (RANS), Large Eddy Simulation (LES) and hybrid LES/RANS models)
are used to model the flow in four ventilated rooms. These describe the flow in a more
physically consistent manner than the commonly used linear RANS models.
The performances of Explicit Algebraic Stress Model (EASM) and, cubic eddyviscosity
RANS model are first analysed on four benchmark flow configurations. They
show significant accuracy improvements when compared to their linear equivalents.
Flows in ventilated rooms are complex. Their numerical modelling required an accurate
definition of the various boundary conditions. This is often lacking in the literature
and hence, as part of this work, measurements in a controlled ventilated office (optimised
for Computational Fluid Dynamics (CFD) modelling) have been done. The measurements
comprise airflow velocities, temperatures, concentration decay and, a careful
description of the room's boundary conditions under six ventilation settings. This room
data is thus seen as ideal for validating of CFD codes when applied to room ventilation
problems.
The numerical investigations show that the predictions with zero- or, one-equation
(k - 1) RANS models (commonly used in room ventilation modelling) are less accurate
than those using two-equation k-e models. The study shows that the accuracy improvements
of the EASM and cubic models are of lesser magnitude when applied to
room ventilation modelling than when applied to the benchmark flow configurations.
The cubic model in particular, besides being more numerically unstable than the other
RANS models, does not always improve flow predictions when compared with its linear
equivalent. The EASM, about 20 to 30% more computationally demanding than
its linear equivalent, improves solution accuracy for most flow considered in this work.
LES predictions have highest level of agreement with measurements. LES is however
too computationally expensive to be used for practical engineering applications. The
novel hybrid RANS/LES model presented appears promising. It has similar accuracy
to LES at lower computational costs.

Item Type:	Thesis or Dissertation (PhD)
Subjects:	Q Science > QA Mathematics
Library of Congress Subject Headings (LCSH):	Air flow -- Mathematical models, Rooms -- Heating and ventilation -- Mathematical models, Turbulence
Official Date:	July 2003
Dates:	Date Event July 2003 Submitted
Institution:	University of Warwick
Theses Department:	School of Engineering
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Tucker, Paul G.
Extent:	xxiii, 228 leaves
Language:	eng

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