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Full-Text Articles in Engineering
On The Role Of Sidewalls In The Transition From Straight To Sinuous Bedforms, Nadim Zgheib, S. Balachandar
On The Role Of Sidewalls In The Transition From Straight To Sinuous Bedforms, Nadim Zgheib, S. Balachandar
Mechanical Engineering Faculty Publications and Presentations
We present results from direct numerical simulation on the transition from straight-crested to sinuous-crested bedforms. The numerical setup is representative of turbulent open channel flow over an erodible sediment bed at a shear Reynolds number of Reτ = 180. The immersed boundary method accounts for the presence of the bed. The simulations are two-way coupled such that the turbulent flow can erode and modify the bed, and in turn, the bed modifies the overlying flow. Coupling from the flow to the bed occurs through the Exner equation, while back coupling from the bed to the flow is achieved by …
Linear Stability Analysis Of Subaqueous Bedforms Using Direct Numerical Simulations, Nadim Zgheib, S. Balachandar
Linear Stability Analysis Of Subaqueous Bedforms Using Direct Numerical Simulations, Nadim Zgheib, S. Balachandar
Mechanical Engineering Faculty Publications and Presentations
We present results on the formation of ripples from linear stability analysis. The analysis is coupled with direct numerical simulations of turbulent open-channel flow over a fixed sinusoidal bed. The presence of the sediment bed is accounted for using the immersed boundary method. The simulations are used to extract the bed shear stress and consequently the sediment transport rate. The approach is different from traditional linear stability analysis in the sense that the phase lag between the bed topology and the sediment flux is obtained from the three-dimensional turbulent simulations. The stability analysis is performed on the Exner equation, whose …