Adaptive Mesh Simulations Of Compressible Flows Using Stabilized Formulations
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Adaptive Mesh Simulations Of Compressible Flows Using Stabilized Formulations
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Author : Camilo Andrés Bayona Roa
language : en
Publisher:
Release Date : 2018
Adaptive Mesh Simulations Of Compressible Flows Using Stabilized Formulations written by Camilo Andrés Bayona Roa and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with categories.
This thesis investigates numerical methods that approximate the solution of compressible flow equations. The first part of the thesis is committed to studying the Variational Multi-Scale (VMS) finite element approximation of several compressible flow equations. In particular, the one-dimensional Burgers equation in the Fourier space, and the compressible Navier-Stokes equations written in both conservative and primitive variables are considered. The approximations made for the VMS formulation are extensively researched; the design of the matrix of stabilization parameters, the definition of the space where the subscales live, the inclusion of the temporal derivatives of the subscales, and the non-linear tracking of the subscales are formulated. Also, the addition of local artificial diffusion in the form of shock capturing techniques is included. The accuracy of the formulations is studied for several regimes of the compressible flow, from aeroacoustic flows at low Mach numbers to supersonic shocks. The second part of the thesis is devoted to make the solution of the smallest fluctuating scales of the compressible flow affordable. To this end, a novel algorithm for $h-$refinement of computational physics meshes in a distributed parallel setting, together with the solution of some refinement test cases in supercomputers are presented. The definition of an explicit a-posteriori error estimator that can be used in the adaptive mesh refinement simulations of compressible flows is also developed; the proposed methodology employs the variational subscales as a local error estimate that drives the mesh refinement. The numerical methods proposed in this thesis are capable to describe the high-frequency fluctuations of compressible flows, especially, the ones corresponding to complex aeroacoustic applications. Precisely, the direct simulation of the fricative [s] sound inside a realistic geometry of the human vocal tract is achieved at the end of the thesis.
Computations Of Unsteady Viscous Compressible Flows Using Adaptive Mesh Refinement In Curvilinear Body Fitted Grid Systems
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Author : Erlendur Steinthorsson
language : en
Publisher:
Release Date : 1994
Computations Of Unsteady Viscous Compressible Flows Using Adaptive Mesh Refinement In Curvilinear Body Fitted Grid Systems written by Erlendur Steinthorsson and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1994 with Viscous flow categories.
Adaptive Mesh Refinement For Finite Element Flow Modeling In Complex Geometries
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Author : Sujata Prakash
language : en
Publisher:
Release Date : 1999
Adaptive Mesh Refinement For Finite Element Flow Modeling In Complex Geometries written by Sujata Prakash and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1999 with categories.
Adaptive mesh refinement is a powerful tool for obtaining the highest solution accuracy for a given computational effort. Over the past decade, many adaptive techniques have been developed and applied to a variety of fluid flow problems. Results obtained for compressible flows, and to an extent, 2D incompressible flows have been impressive, however, similar progress has not been noted for 3D incompressible flows, particularly in complicated geometries. The objective of this thesis was to develop and test an adaptive solution methodology for 3D incompressible flow simulations in domains of arbitrary complexity. To characterize the finite element solution error, the Zienkiewicz-Zhu patch recovery error estimator (LPR) was adopted. An enhanced version of the LPR error estimator was formulated and implemented using 10-noded tetrahedral elements. The enhanced estimator (LPRC) resulted in significantly improved gradient recovery (and consequently, improved error estimates) at virtually no additional computational cost. For mesh refinement, an elemental subdivision procedure was implemented. To enable refinement in complex geometries, a procedure for preserving the boundary integrity of a refined mesh was developed. This methodology can be used for geometric data from any solid modeling (CAD) system provided the data can be exported in the IGES format. A benchmark study of the AMR procedure, in which steady flow over a three-dimensional backward-facing step was simulated, showed that the cumulative computational effort required in the adaptive analysis was lower than that required in a non-adaptive analysis of the same problem. In the second phase of this work, the AMR procedure was applied to modeling flow through two arterial geometries. Specifically, flows in an idealized end-to-side anastomosis and in a human right coronary artery were examined. Both studies assessed whether an AMR analysis could achieve more accurate solutions than conventional analyses that utilize high-resolution meshes whose gradation is based on 'a priori' knowledge of the flow field. It was noted that mesh-independent velocity fields were not very difficult to obtain even in the absence of an adaptive methodology. However, wall shear stress fields were much more difficult to absolutely resolve non-adaptively. Given that shear stresses occurring on arterial walls are widely believed to be a key factor governing the development of arterial disease, it is very important to accurately resolve wall shear stress fields if confidence can be placed in the results of numerical simulations of arterial flow phenomena. These results indicate that wall shear stress is an extremely sensitive measure of spatial resolution, and that the systematic solution-adaptive methodology developed in this thesis is very effective in producing accurately resolved wall shear stress fields.
The Application Of Adaptive Mesh Refinement To The Numerical Simulation Of Compressible Flow
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Author :
language : en
Publisher:
Release Date : 1994
The Application Of Adaptive Mesh Refinement To The Numerical Simulation Of Compressible Flow written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1994 with categories.
This article is based on the adaptive mesh refinement calculation methods developed by M.J. Berger and J. Oliger. It opts for the use of the concept of numerous units formed into a grid, used in solving hyperbolic type equation sets. It combines finite difference forms, opts for the use of Richardson extrapolation techniques to automatically carry out local truncation error estimates, and, for regions with low accuracy, produces new fine mesh local refinements or eliminates old fine mesh refinements which are no longer needed, in order to reach, in the minimum amount of operations, the specified accuracy requirements. Grids are capable of going down into a layer on layer refinement. On the basis of the layered sequence of coverage, each individual grid is a rectangular uniform grid or mesh in any direction desired. This set of algorithms is independent of difference forms used in solutions, is very easy, and combines various types of forms. (AN).
Adaptive Mesh Refinement Method For Cfd Applications
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Author : Oscar Luis Antepara Zambrano
language : en
Publisher:
Release Date : 2019
Adaptive Mesh Refinement Method For Cfd Applications written by Oscar Luis Antepara Zambrano and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with categories.
The main objective of this thesis is the development of an adaptive mesh refinement (AMR) algorithm for computational fluid dynamics simulations using hexahedral and tetrahedral meshes. This numerical methodology is applied in the context of large-eddy simulations (LES) of turbulent flows and direct numerical simulations (DNS) of interfacial flows, to bring new numerical research and physical insight. For the fluid dynamics simulations, the governing equations, the spatial discretization on unstructured grids and the numerical schemes for solving Navier-Stokes equations are presented. The equations follow a discretization by conservative finite-volume on collocated meshes. For the turbulent flows formulation, the spatial discretization preserves symmetry properties of the continuous differential operators and the time integration follows a self-adaptive strategy, which has been well tested on unstructured grids. Moreover, LES model consisting of a wall adapting local-eddy-viscosity within a variational multi-scale formulation is used for the applications showed in this thesis. For the two-phase flow formulation, a conservative level-set method is applied for capturing the interface between two fluids and is implemented with a variable density projection scheme to simulate incompressible two-phase flows on unstructured meshes. The AMR algorithm developed in this thesis is based on a quad/octree data structure and keeps a relation of 1:2 between levels of refinement. In the case of tetrahedral meshes, a geometrical criterion is followed to keep the quality metric of the mesh on a reasonable basis. The parallelization strategy consists mainly in the creation of mesh elements in each sub-domain and establishes a unique global identification number, to avoid duplicate elements. Load balance is assured at each AMR iteration to keep the parallel performance of the CFD code. Moreover, a mesh multiplication algorithm (02) is reported to create large meshes, with different kind of mesh elements, but preserving the topology from a coarser original mesh. This thesis focuses on the study of turbulent flows and two-phase flows using an AMR framework. The cases studied for LES of turbulent flows applications are the flow around one and two separated square cylinders, and the flow around a simplified car model. In this context, a physics-based refinement criterion is developed, consisting of the residual velocity calculated from a multi-scale decomposition of the instantaneous velocity. This criteria ensures grid adaptation following the main vortical structures and giving enough mesh resolution on the zones of interest, i.e., flow separation, turbulent wakes, and vortex shedding. The cases studied for the two-phase flows are the DNS of 2D and 3D gravity-driven bubble, with a particular focus on the wobbling regime. A study of rising bubbles in the wobbling regime and the effect of dimensionless numbers on the dynamic behavior of the bubbles are presented. Moreover, the use of tetrahedral AMR is applied for the numerical simulation of gravity-driven bubbles in complex domains. On this topic, the methodology is validated on bubbles rising in cylindrical channels with different topology, where the study of these cases contributed to having new numerical research and physical insight in the development of a rising bubble with wall effects.
Adaptive Mesh Generation For Viscous Flows Using Delaunay Triangulation
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Author : Dimitri J. Mavriplis
language : en
Publisher:
Release Date : 1988
Adaptive Mesh Generation For Viscous Flows Using Delaunay Triangulation written by Dimitri J. Mavriplis and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1988 with categories.
Mesh And Polynomial Adaptation For High Order Discretizations Of Compressible Flows
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Author : Jean-Sébastien Cagnone
language : en
Publisher:
Release Date : 2013
Mesh And Polynomial Adaptation For High Order Discretizations Of Compressible Flows written by Jean-Sébastien Cagnone and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.
"The aerospace research and industry sectors are relying increasingly on numerical simulations to gain insight into aerodynamic flows. However, the complexity of these flows and the broad range of scales they exhibit still represent a serious challenge to the current generation of computational methods. This thesis presents developments to high-order accurate (> 2nd order) schemes aimed at addressing these limitations. The topic is tackled from the perspectives of enhanced resolution and adaptive error-control. Firstly, an extension of the Lifting-Collocation-Penalty (LCP) scheme to spatially-varying polynomial approximations is presented. This formulation is used to perform efficient polynomial-adaptive computations of compressible flows. The focus is put on the adequate inter-cell flux transfer, and stability analysis of the resulting scheme. Secondly, improved error-control via adjoint-driven mesh refinement is demonstrated. The connection between the global error-norm and the truncation error is established through an adjoint problem. This link provides valuable information about error-propagation patterns, and is shown to be useful for adaptive mesh refinement. " --
Computational Fluid Dynamics 2006
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Author : Herman Deconinck
language : en
Publisher: Springer
Release Date : 2016-04-01
Computational Fluid Dynamics 2006 written by Herman Deconinck and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016-04-01 with categories.
ThisbookcontainstheproceedingsoftheFourthInternationalConference onComputationalFluidDynamics(ICCFD4), heldinGent, Belgiumfrom July10through16,2006. TheICCFDconferenceseriesisanoutcomeofthe mergeroftwoimportantstreamsofconferencesinComputationalFluid- namics: InternationalConferenceonNumericalMethodsinFluidDynamics, ICNMFD(since1996)andInternationalSymposiumonComputationalFluid Dynamics, ISCFD(since1985). In1998itwasdecidedtojointhetwoand ICCFD emerged as a biannual meeting, held in Kyoto in 2000, Sydney in 2002, Toronto in 2004 and Gent in 2006. Thus, the ICCFD series became theleadinginternationalconferenceseriesforscientists, mathematiciansand engineersinterestedinthecomputationof?uid?ow. The4theditionoftheconferencehasattracted200participantsfromall overtheworld;270abstractswerereceived, ofwhich135wereselectedina carefulpeerreviewprocessbytheexecutivecommittee(C. H. Bruneau, J. -J. Chattot, D. Kwak, N. Satofuka, D. W. Zingg, E. DickandH. Deconinck)for oralpresentationandafurther21forposterpresentation. Thepaperscontainedintheseproceedingsprovideanexcellentsnapshot of the ?eld of Computational Fluid Dynamics as of 2006. Invited keynote lecturesbyrenownedresearchersareincluded, withcontributionsinthe?eld ofdiscretizationschemes, high-endcomputingandengineeringchallenges, and two-phase?ow. Thesekeynotecontributionsarecomplementedby137regular papersonthemostdiverseaspectsofCFD: -Innovativealgorithmdevelopmentfor?owsimulation, optimisationandc- trol: higher-ordermethods(DG, FV, FEandRDmethods), iterativemethods andmultigrid, solutionadaptivemeshtechniques, errorestimationandc- trol, parallelalgorithms. -Innovativemodelingof?owphysicsintheareaofcompressibleandinc- pressible ?ows: hypersonic and reacting ?ows, two-phase ?ows, turbulence (LES, DES, DNS, andtransition), vortexdynamics, boundarylayerstability, multi-scalephysics, magnetohydrodynamics. Preface VII -advancedapplicationsusingtheabovementionedinnovativetechnology, and multidisciplinaryapplicationsincludingaero-elasticityandaero-acoustics. ThanksareduetooursponsorsNASA, theFWOResearchFoundation FlandersandtheEuropeanUnionthroughtheEUA4XMarieCurieproject. Inparticular, thegenerousgrantfromNASAisakeyfactorinthesuccessof thisconferenceseriesandthepublicationoftheseProceedings. Wealsowouldliketothankthesta?andPhDstudentsofthevonKarman InstituteandtheDepartmentof?ow, heatandcombustionmechanicsofthe University of Gent, for the help they provided toward the success of this conference. Sint-Genesius-Rode, Belgium HermanDeconinck vonKarmanInstituteforFluidDynamics Ghent, Belgium ErikDick GhentUniversity September2006 ConferenceChair Contents PartIInvitedSpeakers Twonewtechniquesforgeneratingexactlyincompressible approximatevelocities BernardoCockburn. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 RoleofHigh-EndComputinginMeetingNASA'sScience andEngineeringChallenges RupakBiswas, EugeneL. Tu, WilliamR. VanDalsem. . . . . . . . . . . . . . . . 14 RecentAdvancesofMulti-phaseFlowComputationwiththe AdaptiveSoroban-gridCubicInterpolatedPropagation(CIP) Method TakashiYabe, YouichiOgata, KenjiTakizawa. . . . . . . . . . . . . . . . . . . . . . . 29 PartIISchemes OntheComputationofSteady-StateCompressibleFlows UsingaDGMethod HongLuo, JosephD. Baum, RainaldL]ohner. . . . . . . . . . . . . . . . . . . . . . . . 47 Space-TimeDiscontinuousGalerkinMethodforLarge AmplitudeNonlinearWaterWaves YanXu, JaapJ. W. vanderVegt. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 AdiscontinuousGalerkinmethodwi
A Stabilized Reproducing Kernel Formulation For Shock Modeling In Fluids And Fluid Structure Interactive Systems
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Author : Tsunghui Huang
language : en
Publisher:
Release Date : 2020
A Stabilized Reproducing Kernel Formulation For Shock Modeling In Fluids And Fluid Structure Interactive Systems written by Tsunghui Huang and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with categories.
In the extreme event such as air-blast or explosion, strong shocks lead to severe damage and fragmentation in structures. Despite the considerable effort made in recent years, reliable numerical prediction of fragmentation processes in materials and solids under blast loading or shock wave remains challenging. The conventional mesh-based methods (e.g., finite element method (FEM)) are ineffective due to large deformation-induced mesh distortion issues and exhibit non-convergent solutions in fracture problems. The meshfree method, such as reproducing kernel particle method (RKPM), naturally avoids computational difficulties associated with low-quality meshes, allows efficient adaptive refinement, and provides flexible control of smoothness and locality in numerical approximations. The objective of this work is to develop a computational framework for effective modeling of shock dynamics in fluids and fluid-structure interactive systems. In this work, a stabilized RKPM framework for modeling shock waves in fluids is first developed. To capture essential shock physics and to avoid numerical oscillations, a Riemann-enriched smoothed flux divergence with an oscillation limiter is introduced under the stabilized conforming nodal integration (SCNI) framework. Besides, a flux splitting approach is employed to avoid advection-induced instabilities in fluid modeling, and the Monotonic Upstream-Centered Scheme for Conservation Laws (MUSCL)-type oscillation limiter is employed to avoid over and undershooting of the numerical solution at shock front and to capture moving discontinuities with minimal diffusion. The proposed methods, termed MUSCL-SCNI, have been applied to the shock tube problem, compressible flow with vortex, and explosive detonation. Next, an immersed RKPM formulation is developed for an effective body-unfitted spatial discretization of subdomains in heterogeneous materials and fluid structure interaction (FSI) problems involving complex geometries. RKPM naturally avoids computational challenges associated with low-quality meshes, allows efficient adaptive refinement, and provides flexible control of continuity and locality in the numerical approximations. A variational multiscale immersed method (VMIM) is proposed, where the solution fields are decoupled into coarse- and fine-scales, and the fine-scale solution represents the residual of the coarse-scale equations. Under VMIM, the coupling between different subdomains is done through a volumetric constraint, and the embedment of the fine-scale solution into coarse-scale equations yields a stabilized Galerkin formulation with enhanced stability and accuracy. The proposed method is first applied to modeling heterogeneous materials. It is then further extended to shock wave modeling in the FSI systems, where the meshfree algorithm based on MUSCL-SCNI is employed for ensured stability. Finally, the proposed VMIM is applied to air-blast events simulations.
Development And Application Of New Algorithms For The Simulation Of Compressible Flows With Moving Bodies In Three Dimensions
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Author :
language : en
Publisher:
Release Date : 1992
Development And Application Of New Algorithms For The Simulation Of Compressible Flows With Moving Bodies In Three Dimensions written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1992 with categories.
A new CFD capability for compressible flows with moving bodies was developed. The salient features of this capability are: (a) Fast and reliable 3-D unstructured grid generation; (b) Flow solvers for moving frames of reference; (c) Adaptive mesh regeneration during transient runs; (d) On-line display of results; (e) Post-processing and movie-making capability.