Fluid flow features inside an enclosure device used for measuring volatile emissions from quiescent surfaces

Name: Izabele Venturott Ferreira Toniato
Type: MSc dissertation
Publication date: 19/02/2020
Advisor:

Namesort descending Role
Jane Meri Santos Advisor *

Examining board:

Namesort descending Role
Ademir Abdala Prata Junior External Examiner *
Jane Meri Santos Advisor *
Neyval Costa Reis Jr. Internal Examiner *
Ramon Silva Martins Co advisor *

Summary: Odorous gases generated by domestic and industrial wastewater treatment plants and
other industrial processes can cause discomfort in the population living nearby and may generate
complaints to the local environmental agency. Some of the odorous sources in these facilities
are characterized as passive areas sources and their emission rate can be measured by portable
wind tunnels. It is a bottom opened devices positioned over an odor-emitting surface. However,
there is not a universally adopted wind tunnel model yet. The objective of this work consists in
analyzing the air flow patterns inside the tunnel positioned over different rough surfaces and
to verify if it reproduces the friction velocity encountered in atmospheric flows. The fluid flow
was modeled using the fundamental equations of mass and momentum conservation. These
equations were solved by means of a numerical solution based on the finite volume method using
an unstructured mesh formed by tetrahedral and prismatic volume elements.
The results showed that there are recirculation zones inside the tunnel and an acceleration
after the inlet curve. The velocity vectors showed a deceleration in the flow for surfaces with
higher roughness value and the turbulence intensity was lower for the same surfaces. The highest
values of the friction velocity at the emitting surface were found at the entrance of the tunnel’s
main section and were decreasing as the flow develops in the main flow direction. The mean
friction velocity varied between 0.14 m s−1
(for the lowest roughness) and 0.23 m s−1
(for the
highest roughness). Different inlet velocities were also analyzed for smooth surface and the mean
friction velocity varied between 0.06 m s−1
(for the lowest inlet velocity) and 0.14 m s−1
(for
the highest inlet velocity). These values are in agreement with the friction velocity values found
in atmospheric flows for some ranges of wind flow velocity.

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