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Ray R.K.,Indian Institute of Technology Guwahati | Ray R.K.,Laboratoire dHydraulique Saint Venant
Journal of Scientific Computing | Year: 2011

In the present work, a numerical study is made using a recently developed Higher Order Compact (HOC) finite difference scheme to test its capacity in capturing the very complex flow phenomenon of unsteady flow past a rotating and translating circular cylinder. The streamfunction-vorticity formulation of the Navier-stokes equations in cylindrical polar coordinate are considered as the governing equations. In the present investigation, flow is computed for a fixed Reynolds number (Re) 200 and rotational parameter values 0.5, 1.0, 2.07 and 3.25 are considered. Firstly, the flow patterns for different α values and for long time range are computed and qualitative comparisons are made with existing experimental and numerical results. Then, as a further check on the consistency of the experimental and present numerical results, quantitative comparisons are made for the velocity profiles at several locations. All these qualitative and quantitative comparisons show excellent agreements with existing experimental and numerical results. © 2010 Springer Science+Business Media, LLC. Source


Yates M.L.,Bureau de Recherches Geologiques et Minieres | Yates M.L.,Laboratoire dHydraulique Saint Venant | Le Cozannet G.,Bureau de Recherches Geologiques et Minieres
Natural Hazards and Earth System Sciences | Year: 2012

The coastal zone is a complex environment in which a variety of forcing factors interact causing shoreline evolution. Coastal managers seek to predict coastal evolution and to identify regions vulnerable to erosion. Here, a Bayesian network is developed to identify the primary factors influencing decadal-scale shoreline evolution of European coasts and to reproduce the observed evolution trends. Sensitivity tests demonstrate the robustness of the model, showing higher predictive capabilities for stable coasts than for eroding coasts. Finally, the study highlights the need to update and expand large-scale coastal data sets, particularly by including local scale processes and anthropogenic impacts. © 2012 Author(s). Source


Ray R.K.,Laboratoire dHydraulique Saint Venant
World Academy of Science, Engineering and Technology | Year: 2010

An unstructured finite volume numerical model is presented here for simulating shallow-water flows with wetting and drying fronts. The model is based on the Green's theorem in combination with Chorin's projection method. A 2nd-order upwind scheme coupled with a Least Square technique is used to handle convection terms. An Wetting and drying treatment is used in the present model to ensures the total mass conservation. To test it's capacity and reliability, the present model is used to solve the Parabolic Bowl problem. We compare our numerical solutions with the corresponding analytical and existing standard numerical results. Excellent agreements are found in all the cases. Source


Ray R.K.,Laboratoire dHydraulique Saint Venant | Nguyen K.D.,Laboratoire dHydraulique Saint Venant
World Academy of Science, Engineering and Technology | Year: 2010

An unstructured finite volume numerical model is presented here for simulating shallow-water flows with wetting and drying fronts. The model is based on the Green's theorem in combination with Chorin's projection method. A 2 nd-order upwind scheme coupled with a Least Square technique is used to handle convection terms. An Wetting and drying treatment is used in the present model to ensures the total mass conservation. To test it's capacity and reliability, the present model is used to solve the Parabolic Bowl problem. We compare our numerical solutions with the corresponding analytical and existing standard numerical results. Excellent agreements are found in all the cases. Source


Violeau D.,Laboratoire dHydraulique Saint Venant | Leroy A.,Laboratoire dHydraulique Saint Venant
Journal of Computational Physics | Year: 2015

A classical incompressible algorithm for Smoothed Particle Hydrodynamics (ISPH) is analyzed in terms of critical time step for numerical stability. For this purpose, a theoretical linear stability analysis is conducted for unbounded homogeneous flows, leading to an analytical formula for the maximum CFL (Courant-Friedrichs-Lewy) number as a function of the Fourier number. This gives the maximum time step as a function of the fluid viscosity, the flow velocity scale and the SPH discretization size (kernel standard deviation). Importantly, the maximum CFL number at large Reynolds number appears twice smaller than with the traditional Weakly Compressible (WCSPH) approach. As a consequence, the optimal time step for ISPH is only five times larger than with WCSPH. The theory agrees very well with numerical data for two usual kernels in a 2-D periodic flow. On the other hand, numerical experiments in a plane Poiseuille flow show that the theory overestimates the maximum allowed time step for small Reynolds numbers. © 2015 Elsevier Inc. Source

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