Scale-Resolving Simulation Techniques in Industrial CFD

Field observations presented indicate that scale has a preference to deposit at positions in production wells where irregularities in the flow pattern occur. This could be at bottle necks where the shear forces and turbulence are particularly high, or after a tubing expansion where back currents and eddies occur. One negative consequence of this is that critical well equipment such as Inflow Control Valves (ICV), Inflow Control Devices (ICD) and Down Hole Safety Valves (DHSV) will be particularly exposed to scale deposition, which may cause equipment failure and increased operational risk.

Acta Mechanica Sinica, 2014

Eddy-damping quasinormal Markovian (EDQNM) theory is employed to calculate the resolved-scale spectrum and transfer spectrum, based on which we investigate the resolved-scale scaling law. Results show that the scaling law of the resolved-scale turbulence, which is affected by several factors, is far from that of the full-scale turbulence and should be corrected. These results are then applied to an existing subgrid model to improve its performance. A series of simulations are performed to verify the necessity of a fixed scaling law in the subgrid modeling. Keywords Scaling law • Large-eddy simulation • CZZS model 1 Introduction Kolmogorov introduced the 2/3 scaling law for the secondorder structure function in isotropic turbulence, which is

2019

Along with advances in computer technology, numerical simulation has been widely used in the analysis of marine hydrodynamic problems, especially for the multiphase flow. According to the resolution-scales, the simulation of multiphase flow can be performed in macroscale, mesoscale and microscale, corresponding numerical methods, i.e. the RANS/DES approach with VOF method, Euler-Lagrange method, Moving Particle Semi-implicit (MPS) method and DNS method, are demonstrated in the present paper. The numerical results obtained by those methods are in consistent with the experimental ones and other’s research. It is concluded that with further development of theoretical study and numerical methods, the present numerical methods can deal with complex multiphase flow problems in multiple scales. Efficiency and accuracy need to be focused in the future development of the numerical model and CFD solver.

33rd Aerospace Sciences Meeting and Exhibit, 1995

A new concept, multiple scale simulation (MSS), is presented in this paper. The basic idea is that the ow is decomposed into several component groups according to spatial and temporal length scales. Each group has its own subdomain, governing system, mesh size, and discretization method. The simulation is then performed groupwise. This approach has been successfully applied in combination with the intergrid dissipation technique for simulation of transitional and turbulent ow in 3-D boundary layers, and it is feasible for 3-D airfoils and other more complex con gurations. MSS should prove to ameliorate the scale problems associated with conventional direct numerical simulation.

Physics of Fluids, 2013

Physics of Fluids, 1999

Scale-similar models employ multiple filtering operations to identify the smallest resolved scales, which have been shown to be the most active in the interaction with the unresolved subgrid scales. They do not assume that the principal axes of the strain-rate tensor are aligned with those of the subgrid-scale stress (SGS) tensor, and allow the explicit calculation of the SGS energy. They can provide backscatter in a numerically stable and physically realistic manner, and predict SGS stresses in regions that are well correlated with the locations where large Reynolds stress occurs. In this paper, eddy viscosity and mixed models, which include an eddy-viscosity part as well as a scale-similar contribution, are applied to the simulation of two flows, a high Reynolds number plane channel flow, and a three-dimensional, nonequilibrium flow. The results show that simulations without models or with the Smagorinsky model are unable to predict nonequilibrium effects. Dynamic models provide a...

Journal of physics, 2015

The accurate prediction of the performances of axial water turbines and naval propellers is a challenging task, of great practical relevance. In this paper a numerical prediction strategy, based on the combination of a trusted CFD solver and a calibrated mass transfer model, is applied to the turbulent flow in axial turbines and around a model scale naval propeller, under non-cavitating and cavitating conditions. Some selected results for axial water turbines and a marine propeller, and in particular the advantages, in terms of accuracy and fidelity, of Scale-Resolving Simulations (SRS), like SAS (Scale Adaptive Simulation) and Zonal-LES (ZLES) compared to standard RANS approaches, are presented. Efficiency prediction for a Kaplan and a bulb turbine was significantly improved by use of the SAS SST model in combination with the ZLES in the draft tube. Size of cavitation cavity and sigma break curve for Kaplan turbine were successfully predicted with SAS model in combination with robust high resolution scheme, while for mass transfer the Zwart model with calibrated constants were used. The results obtained for a marine propeller in non-uniform inflow, under cavitating conditions, compare well with available experimental measurements, and proved that a mass transfer model, previously calibrated for RANS (Reynolds Averaged Navier Stokes), can be successfully applied also within the SRS approaches.

1998

No part of this book may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from DCW Industries, Inc .

International Journal of Heat and Fluid Flow

In the last decades, one of the main objectives pursued in the field of computational fluid dynamics has been the development of turbulent flow models and simulations techniques capable of generating predictions of flow patterns accurate enough to many industrial applications in a reasonable wall-clock time and at an acceptable cost. Very often, a trade-off has to be sought between the engineer's expectations regarding the accuracy of the model and the limited computational resources available. In that framework, the present contribution aims at demonstrating the capabilities of the SST-SAS approach which is considered as an intermediate model with respect to accuracy and computational requirements. To that end, the turbulent flow through a tube bundle was selected as test case. Preliminary sensitivity analyses were carried out to properly choose the residuals tolerance level, duration of the physical time integration, mesh size and time step value. The SST-SAS results are compared with available experimental data as well as with different simulations results taken from the literature. A quantitative scoring criterion was defined to sort out the different models results: the SST-SAS ranked first.

EPJ Web of Conferences

In this paper, the results of a numerical simulation of the air flow in the vicinity of a parallelepiped fixed on a plate are presented. The 3D calculations were performed with the ANSYS Fluent software using scale-resolving DES approach. The obtained results are compared with the experimental data and with the results of the previous numerical calculation.

2015

Sub-grid scale (SGS) models are required in order to model the influence of the unresolved small scales on the resolved scales in large-eddy simulations (LES), the flow at the smallest scales of turbulence. In the following work two SGS models are presented and deeply analyzed in terms of accuracy through several LESs with different spatial resolutions, i.e. grid spacings. The first part of this thesis focuses on the basic theory of turbulence, the governing equations of fluid dynamics and their adaptation to LES. Furthermore, two important SGS models are presented: one is the Dynamic eddy-viscosity model (DEVM), developed by \cite{germano1991dynamic}, while the other is the Explicit Algebraic SGS model (EASSM), by \cite{marstorp2009explicit}. In addition, some details about the implementation of the EASSM in a Pseudo-Spectral Navier-Stokes code \cite{chevalier2007simson} are presented. The performance of the two aforementioned models will be investigated in the following chapters, ...

Journal of Fluid Mechanics, 1992

New subgrid-scale models for the large-eddy simulation of compressible turbulent flows are developed and tested based on the Favre-filtered equations of motion for an ideal gas. A compressible generalization of the linear combination of the Smagorinsky model and scale-similarity model, in terms of Fame-filtered fields, is obtained for the subgrid-scale stress tensor. An analogous thermal linear combination model is also developed for the subgrid-scale heat flux vector. The two dimensionless constants associated with these subgrid-scale models are obtained by correlating with the results of direct numerical simulations of compressible isotropic turbulence performed on a 968 grid using Fourier collocation methods. Extensive comparisons between the direct and modelled subgrid-scale fields are provided in order to validate the models. A large-eddy simulation of the decay of compressible isotropic turbulence conducted on a coarse 32a gridis shown to yield results that are in excellent agreement with the fine-grid direct simulation. Future applications of these compressible subgrid-scale models to the large-eddy simulation of more complex supersonic flows are discussed briefly.

Computers & Fluids, 2001

Direct numerical simulation of an equilibrium turbulent pipe¯ow at a Reynolds number of 2500, based on bulk velocity and pipe diameter, has been carried out with a grid of about 7:4 Â 10 5 points and a fully resolved wall layer. The simulation ®lls the existing gap in the availability of accurate turbulence data in the low Reynolds number range, so that the sensitivity of the main statistical quantities to the Reynolds number eects could be completed. The systematic dependence of the turbulent stress tensor components upon Re in the near wall region, when the normalization is based upon the wall shear stress and kinematic viscosity, is con®rmed. Normalization based on the Kolmogorov velocity and length scales as suggested by Antonia and Kim [1] in the context of plane channel¯ow, proves eective also for pipe¯ow at lower Re. The high values attained by the fourth-order moments of the radial and azimuthal velocities are shown to be of truly physical nature and to be related with rare and energetic events characterizing the whole wall layer. Vorticity dynamics analysis suggests that the origin of the high¯atness factors is associated with the interaction of counter-rotating streamwise vortices with the wall. Analysis of the transport equations of the turbulent kinetic energy shows that the production, turbulent dissipation and viscous diusion rates, the leading terms of the budget, increase considerably with Re for y < 20. Ó

Journal of Turbulence, 2005

In this work coherent vortex simulation (CVS) and stochastic coherent adaptive large eddy simulation (SCALES) simulations of decaying incompressible isotropic turbulence are compared to DNS and large eddy simulation (LES) results. Current LES relies on, at best, a zonally adapted filter width to reduce the computational cost of simulating complex turbulent flows. While there is an improvement over a uniform

2020

The quest to understand turbulent flows continues to be as important as it was during the previous century. Present work shows that if a &#39;laminar&#39; solution to Navier -Stokes equations can be found then skin friction and heat transfer coefficients for the turbulent case can readily be obtained. There is no need for Reynolds averaging and turbulence modelling. This can be done by defining a turbulence scaling factor which converts &#39;laminar&#39; diffusivities to turbulent diffusivities. Using turbulent diffusivities in the laminar skin friction coefficient formula and laminar heat transfer coefficient formula gives the corresponding turbulent formula. Five different test cases with credible experimental measurements have been used to show the success of the present approach. This work also gives the lengths of internally generated turbulent eddies and roughness created turbulent eddies. If main flow mixes the turbulent eddies , smaller eddies are merged by the larger ones a...