Numerical Simulation of Flow Over Urban-Like Topographies and Evaluation of Turbulence Temporal Attributes
Journal Article - Open Access
Baylor University Waco United States
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We have used large-eddy simulation with an immersed boundary method to study turbulent flows over distributions of uniform height, staggered cubes. The computational domains were designed such that both the roughness sublayer and a region of the inertial layer are resolved. With this, we record vertical profiles of time series of fluctuating streamwise and vertical velocity at different locations throughout the domain. Contour images of these fluctuating quantities shown relative to elevation and time are studied contour images of Reynolds shear stresses owing to sweeps and ejections are also studied. These images show that periods of momentum excess deficit in the inertiallayer precede excitation subdual of cube-scale coherent vortices in the roughness sublayer. We compute this time lag termed advective lag and demonstrate that it scales linearly with wall-normal elevation. The advective lag is attributed to coherent, low andhigh-momentum regions in the aloft inertial layer.
- Fluid Mechanics