scholarly journals Advances in Numerical Reynolds-Averaged Navier–Stokes Modelling of Wave-Structure-Seabed Interactions and Scour

2021 ◽  
Vol 9 (6) ◽  
pp. 611
Author(s):  
Pilar Díaz-Carrasco ◽  
Sergio Croquer ◽  
Vahid Tamimi ◽  
Jay Lacey ◽  
Sébastien Poncet
Keyword(s):  
Sediment Transport ◽  
Numerical Modelling ◽  
Review Paper ◽  
Fluid Phase ◽  
Wave Structure ◽  
Numerical Approach ◽  
Navier Stokes ◽  
Future Prospects ◽  
Rans Equations ◽  
Reynolds Averaged Navier Stokes

This review paper presents the recent advances in the numerical modelling of wave–structure–seabed interactions. The processes that are involved in wave–structure interactions, which leads to sediment transport and scour effects, are summarized. Subsequently, the three most common approaches for modelling sediment transport that is induced by wave–structure interactions are described. The applicability of each numerical approach is also included with a summary of the most recent studies. These approaches are based on the Reynolds-Averaged Navier–Stokes (RANS) equations for the fluid phase, and mostly differ in how they tackle the seabed response. Finally, future prospects of research are discussed.

scholarly journals RANS MODELLING OF CROSS-SHORE SEDIMENT TRANSPORT AND MORPHODYNAMICS IN THE SWASH-ZONE

2020 ◽  
pp. 14
Author(s):  
Joost Kranenborg ◽  
Geert Campmans ◽  
Niels Jacobsen ◽  
Jebbe van der Werf ◽  
Robert McCall ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Numerical Model ◽  
Navier Stokes ◽  
Swash Zone ◽  
Rans Equations ◽  
Model Based ◽  
Numerical Studies ◽  
Reynolds Averaged Navier Stokes ◽  
Averaged Models

Most numerical studies of sediment transport in the swash zone use depth-averaged models. However, such models still have difficulty predicting transport rates and morphodynamics. Depth-resolving models could give detailed insight in swash processes but have mostly been limited to hydrodynamic predictions. We present a depth-resolving numerical model, based on the Reynolds Averaged Navier-Stokes (RANS) equations, capable of modelling sediment transport and morphodynamics in the swash zone.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/PB8Vs0LJq88

scholarly journals Reynolds-averaged Navier–Stokes equations with explicit data-driven Reynolds stress closure can be ill-conditioned

2019 ◽  
Vol 869 ◽  
pp. 553-586 ◽  
Author(s):  
Jinlong Wu ◽  
Heng Xiao ◽  
Rui Sun ◽  
Qiqi Wang
Keyword(s):  
Reynolds Stress ◽  
Condition Number ◽  
Stokes Equations ◽  
Plane Channel ◽  
Channel Flows ◽  
Data Driven ◽  
Navier Stokes ◽  
Rans Equations ◽  
Reynolds Averaged Navier Stokes ◽  
Stress Models

Reynolds-averaged Navier–Stokes (RANS) simulations with turbulence closure models continue to play important roles in industrial flow simulations. However, the commonly used linear eddy-viscosity models are intrinsically unable to handle flows with non-equilibrium turbulence (e.g. flows with massive separation). Reynolds stress models, on the other hand, are plagued by their lack of robustness. Recent studies in plane channel flows found that even substituting Reynolds stresses with errors below 0.5 % from direct numerical simulation databases into RANS equations leads to velocities with large errors (up to 35 %). While such an observation may have only marginal relevance to traditional Reynolds stress models, it is disturbing for the recently emerging data-driven models that treat the Reynolds stress as an explicit source term in the RANS equations, as it suggests that the RANS equations with such models can be ill-conditioned. So far, a rigorous analysis of the condition of such models is still lacking. As such, in this work we propose a metric based on local condition number function for a priori evaluation of the conditioning of the RANS equations. We further show that the ill-conditioning cannot be explained by the global matrix condition number of the discretized RANS equations. Comprehensive numerical tests are performed on turbulent channel flows at various Reynolds numbers and additionally on two complex flows, i.e. flow over periodic hills, and flow in a square duct. Results suggest that the proposed metric can adequately explain observations in previous studies, i.e. deteriorated model conditioning with increasing Reynolds number and better conditioning of the implicit treatment of the Reynolds stress compared to the explicit treatment. This metric can play critical roles in the future development of data-driven turbulence models by enforcing the conditioning as a requirement on these models.

A Numerical Method for 3D Turbomachinery Aeroelasticity

2004 ◽  
Author(s):  
Paola Cinnella ◽  
Emanuele Cappiello ◽  
Pietro De Palma ◽  
Michele Napolitano ◽  
Giuseppe Pascazio
Keyword(s):  
Rigid Body ◽  
Numerical Method ◽  
Integral Form ◽  
Navier Stokes ◽  
Moving Grid ◽  
Time Step ◽  
Rans Equations ◽  
Standard Configuration ◽  
Reynolds Averaged Navier Stokes

This work provides an extension to 3D aeroelastic problems of a recently developed numerical method for turbomachinery aeroelasticity. The unsteady Euler or Reynolds-averaged Navier-Stokes (RANS) equations are solved in integral form, the blade passages being discretised using a deforming grid. The grid is regenerated at each time step using a novel methodology, that automatically avoids grid lines overlapping and guarantees the smoothness of the regenerated mesh. Firstly, the method has been validated versus the 2D 4th Aeroelastic Turbine Standard Configuration. Both inviscid and viscous turbulent computations have been performed, and the results previously obtained usind a different moving grid strategy have been recovered. In order to prove the robustness of the proposed deforming grid methodology, the same case has also been computed with the blade under-going large torsion displacements, the regenerated grid always preserving a good smoothness. Then, the methodology has been validated versus the 3D 4th Standard Aeroelastic Configuration, that involves a rigid body blade motion. Finally, a more severe 3D configuration, involving a clamped-beam-like blade deformation, has been considered.

scholarly journals Jet Noise in Airframe Integration and Shielding

2020 ◽  
Vol 10 (2) ◽  
pp. 511
Author(s):  
Saman Salehian ◽  
Reda Mankbadi
Keyword(s):  
Experimental Data ◽  
Large Eddy Simulation ◽  
Jet Noise ◽  
Numerical Approach ◽  
Navier Stokes ◽  
Complex Geometries ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Reynolds Averaged Navier Stokes

This paper reviews and presents new results on the effect of airframe integration and shielding on jet noise. Available experimental data on integration effects are analyzed. The available options for the computation of jet noise are discussed, and a practical numerical approach for the present topic is recommended. Here, it is demonstrated how a hybrid large eddy simulation—unsteady Reynolds-averaged Navier-Stokes approach can be implemented to simulate the effect of shielding on radiated jet noise. This approach provides results consistent with the experiment and suggests a framework for studying more complex geometries involving airframe integration effects.

scholarly journals VIScous Vorticity Equation (VISVE) for Turbulent 2-D Flows with Variable Density and Viscosity

2020 ◽  
Vol 8 (3) ◽  
pp. 191 ◽  
Author(s):  
Spyros A. Kinnas
Keyword(s):  
Variable Viscosity ◽  
Variable Density ◽  
Vorticity Equation ◽  
Navier Stokes ◽  
Cavitating Flows ◽  
Rans Equations ◽  
Reynolds Averaged Navier Stokes

The general vorticity equation for turbulent compressible 2-D flows with variable viscosity is derived, based on the Reynolds-Averaged Navier-Stokes (RANS) equations, and simplified versions of it are presented in the case of turbulent or cavitating flows around 2-D hydrofoils.

Principles and approaches for numerical modelling of sediment transport in sewers

1995 ◽  
Vol 31 (7) ◽  
pp. 107-115 ◽  
Author(s):  
Ole Mark ◽  
Cecilia Appelgren ◽  
Torben Larsen
Keyword(s):  
Mathematical Model ◽  
Sediment Transport ◽  
Numerical Modelling ◽  
Simple Application ◽  
Sewer Systems ◽  
Sediment Deposits ◽  
Model Mouse ◽  
Modelling Approaches

A study has been carried out with the objectives of describing the effect of sediment deposits on the hydraulic capacity of sewer systems and to investigate the sediment transport in sewer systems. A result of the study is a mathematical model MOUSE ST which describes sediment transport in sewers. This paper discusses the applicability and the limitations of various modelling approaches and sediment transport formulations in MOUSE ST. Further, the paper presents a simple application of MOUSE ST to the Rya catchment in Gothenburg, Sweden.

Fabrication Technologies and Applications of Graphene-based co-polymeric Nano-composites: its challenges and Future works

2019 ◽  
Vol 09 ◽  
Author(s):  
Pratik Chhapia ◽  
Harshad Patel
Keyword(s):  
Review Paper ◽  
Polymeric Coating ◽  
Nano Composites ◽  
Future Prospects ◽  
Electrical And Optical Properties ◽  
In Situ Techniques ◽  
Surface Areas ◽  
Ink Jet ◽  
Enhanced Conductivity

: Graphene based co-polymeric Nano-composites explored and trending in various applications as ascribing to its enhanced conductivity and controlled modification with wide specific surface areas. With the number of advantages of co-polymeric coating on Graphene or Graphene sheets and their derivatives, Graphene based co-polymeric Nano-composites fabricated by various techniques (deposition, ink jet, electro spinning, spin coating, in-situ techniques, etc.) and different conducting co-polymers show its exceptional chemical, mechanical, electrical and optical properties. Therefore, in the today’s world with greater quantities of various properties of co-polymer with Graphene based Nano-composites with enhanced stability, selectivity and sensitivity have been formed. In this review paper, we have particularly focused on recent advancing in fabrication of different technologies with the help of Graphene based co-polymeric Nano-composites and its various trending and future applications. Finally, on the personal standpoint; the key challenges of Graphene based co-polymeric Nano-composites are mentioned in hope to shed a light on their potential future prospects.

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