Ducts can be found in ventilation systems, cooling ducts and blade passages of turbines,
centrifugal pumps and many other engineering installations. The properties of the flow in
ducts can significantly affect the performance and efficiency of these installation areas. The
majority of the flows in ducts and engineering applications are turbulent.
The work presented in this thesis focuses on the analysis of turbulent flows inside square
sectioned ducts and ducts with bends. The accuracy of three different high resolution high
order schemes in the context of Implicit Large Eddy Simulation (ILES) is analysed. The
influence of a low Mach limiting technique, Low Mach Number Treatment (LMNT) is also
studied. The schemes employed are Monotonic Upwind Scheme for Scalar Conservation
Laws (MUSCL) with a 2nd order Monotonized Central (MC) and 5th order limiter, and a
9th order Weighted Essential Non-Oscillatory (WENO) limiter.
The first case studied is a duct of square cross section . In the absence of experimental
data for the duct case, the data from a plain channel flow is used to shed light on the results.
The flow analysis points out the generation of secondary motions created by the existence of
surrounding walls. All schemes employed lead to a similarly developed turbulent flow that
is used to provide the turbulent boundary profile for the following case. LMNT proves to
significantly assist MUSCL 2nd and 5th, that use it, in providing a turbulent profile similar
to that of WENO 9th that did not employ the technique but is inherently less dissipative.
The second case under study is that of a square sectioned duct with a 90o bend. The
simulation output is in good agreement both qualitatively and quantitatively with the experimental
data available in the literature. The generation of secondary flows inside the bend
is observed without flow separation. Although the turbulent flow entering the domain is
almost the same for all cases, differences between the schemes are noticed especially after
the middle of the bend. LMNT leads to an overprediction of turbulence after that area for
both schemes employing it while WENO 9th without LMNT provides the most accurate
results compared to those provided by the experiment.
The results demonstrate applicability of ILES to strongly confined flows with secondary
motions and shed light on cognitive properties of a wide range of state of the art schemes
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