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International Journal of Multiphase Flow



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Bluff body, shallow flow, fluid structure interaction


An enhanced picture of the formation of fluid structures including the effect of the free surface and the bed is captured via a numerical solution of flow past a bed mounted bluffbody. A numerical comparison for the fluid structures observed in a time-averaged field of the shallow-wake flow behind a bluffbody utilizing the rigid-lid assumption and volume of fluid method is carried out in this study to bring forth the shortcomings in previous studies. The transient three-dimensional governing Navier–Stokes equations are computationally solved using a finite volume technique with Detached Eddy Simulation as a turbu- lence model. A flat wave model is used with the volume of fluid method to simulate the free surface of the water-air interface. The flow structures in the shallow-wake are qualitatively identified using the λ2 -criterion. In addition to the well-known features present in traditional shallow flows, other distinc- tive features are captured at the near-bed and near-surface locations. The formation of these structures and their dynamics are addressed in this paper. It is found that use of the volume of fluid method, which provides a more accurate representation of the free surface, has a significant impact on the structures’ de- velopment at the near-surface location in the far-wake and on the streamtraces in front of the bluffbody. Unique streamwise oriented structures are captured in the near-bed and free surface, which transport the fluid particles from the centre of the wake to the outer region. To the contrary, the fluid structures with the rigid-lid assumption are not completely developed near the free surface.

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Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.