Study of pulsating flows inside an axially corrugated geometry

• In this study the influence of flow pulsations on the intrinsic flow structures found within corrugated-pipe like geometries is explored numerically. An axisymmetric geometry with wavy-walls is taken under consideration. Two different pulsatile inlet conditions are considered which consist of sinusoidal pulse form and a distinct pulsation frequency: 80Hzand 160Hz. The 3D, incompressible and turbulent gas flow is simulated using a Large Eddy Simulation (LES) methodology with a wall adapting local eddy viscosity (WALE) subgrid scale (SGS) model. A solver validation study is firstly presented based on the Direct Numerical Simulation (DNS) data of the wavy-wall benchmark case (data set available at http://cfd.mace.manchester.ac.uk/ercoftac/database/cases/case77/Case_data/). A subsequent grid resolution study is completed in in order to determinean appropriate mesh size. This is followed by a comparison between the flow profiles and coherent structures for the pulsatile flow under consideration. The coherent flow structures are exposed using a Proper Orthogonal Decomposition (POD) approach and spectral analysis. The appearance of an axial mode is highlighted. Spectral analysis indicates that this particular flow mode is driven by the flow pulsations. Furthermore, an asymmetric oscillatory mode is highlighted using the POD approach. Spectral analysis revealed that up to 500Hz the most dominant spectral content appeared in the expansion regions, enveloping the shear-layer/recirculation bubble, of the geometry. Increasing beyond 500Hz the strongest spectral content appeared inside a narrow, confined region within the shear-layer.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik -- Strömningsmekanik och akustik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering -- Fluid Mechanics and Acoustics (hsv//eng)

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