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Reduced Order Models for Underfloor Ventilation Systems


K. Chung

Master Thesis, FS 09

A room with displacement ventilation is simulated using computational fluid dynamics software. Displacement ventilation is an energy efficient method of air conditioning and ventilating; cool air enters the room from the floor level which rises to the ceiling due to heat sources. This forms a stratification of cool and warm regions, allowing extraction of the warm air from the ceiling. The proper orthogonal decomposition (POD) is applied to the simulation data to yield finite subspaces that capture the underlying physical features of the flow. A low-order model of the air velocity and temperature distributions is then obtained by projecting the governing partial differential equations onto a POD subspace using Galerkin projection. The projection yields a small set of ordinary differential equations (ODEs) that approximate the fluid dynamics. A case study performed on a 2D convective flow inside a cavity shows that the inclusion of a turbulence model -- also needed in displacement entilation--introduces difficulty in obtaining ODEs that estimate the solution. However, case studies performed on the heat diffusion equation and a 2D convective flow inside a cavity without a turbulence model show that three to six projected ODEs estimate the solutions within 10% RMS error over the domain.


Type of Publication:

(12)Diploma/Master Thesis

M. Morari

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author = "Chung, Kimberly H.",
title = "Reduced Order Models for Underfloor Ventilation Systems",
school = "Eidgen{\"o}ssische Technische Hochschule Z{\"u}rich (ETH Zurich)",
year = "2009",
month = "April"
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