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Article
Publication date: 29 August 2019

Song Gao, Jory Seguin, Wagdi G. Habashi, Dario Isola and Guido Baruzzi

This work aims to describe the physical and numerical modeling of a CFD solver for hypersonic flows in thermo-chemical non-equilibrium. This paper is the second of a…

Abstract

Purpose

This work aims to describe the physical and numerical modeling of a CFD solver for hypersonic flows in thermo-chemical non-equilibrium. This paper is the second of a two-part series that concerns the application of the solver introduced in Part I to adaptive unstructured meshes.

Design/methodology/approach

The governing equations are discretized with an edge-based stabilized finite element method (FEM). Chemical non-equilibrium is simulated using a laminar finite-rate kinetics, while a two-temperature model is used to account for thermodynamic non-equilibrium. The equations for total quantities, species and vibrational-electronic energy conservation are loosely coupled to provide flexibility and ease of implementation. To accurately perform simulations on unstructured meshes, the non-equilibrium flow solver is coupled with an edge-based anisotropic mesh optimizer driven by the solution Hessian to carry out mesh refinement, coarsening, edge swapping and node movement.

Findings

The paper shows, through comparisons with experimental and other numerical results, how FEM + anisotropic mesh optimization are the natural choice to accurately simulate hypersonic non-equilibrium flows on unstructured meshes. Three-dimensional test cases demonstrate how, for high-speed flows, shocks resolution, and not necessarily boundary layers resolution, is the main driver of solution accuracy at walls. Equally distributing the error among all elements in a suitably defined Riemannian space yields highly anisotropic grids that feature well-resolved shock waves. The resulting high level of accuracy in the computation of the enthalpy jump translates into accurate wall heat flux predictions. At the opposite end, in all cases examined, high-quality but isotropic unstructured meshes gave very poor solutions with severely inadequate heat flux distributions not even featuring expected symmetries. The paper unequivocally demonstrates that unstructured anisotropically adapted meshes are the best, and may be the only, way for accurate and cost-effective hypersonic flow solutions.

Originality/value

Although many hypersonic flow solvers are developed for unstructured meshes, few numerical simulations on unstructured meshes are presented in the literature. This work demonstrates that the proposed approach can be used successfully for hypersonic flows on unstructured meshes.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 30 no. 2
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 21 June 2019

Jory Seguin, Song Gao, Wagdi George Habashi, Dario Isola and Guido Baruzzi

This paper aims to describe the physical and numerical modeling of a new computational fluid dynamics solver for hypersonic flows in thermo-chemical non-equilibrium. The…

Abstract

Purpose

This paper aims to describe the physical and numerical modeling of a new computational fluid dynamics solver for hypersonic flows in thermo-chemical non-equilibrium. The code uses a blend of numerical techniques to ensure accuracy and robustness and to provide scalability for advanced hypersonic physics and complex three-dimensional (3D) flows.

Design/methodology/approach

The solver is based on an edge-based stabilized finite element method (FEM). The chemical and thermal non-equilibrium systems are loosely-coupled to provide flexibility and ease of implementation. Chemical non-equilibrium is modeled using a laminar finite-rate chemical kinetics model while a two-temperature model is used to account for thermodynamic non-equilibrium. The systems are solved implicitly in time to relax numerical stiffness. Investigations are performed on various canonical hypersonic geometries in two-dimensional and 3D.

Findings

The comparisons with numerical and experimental results demonstrate the suitability of the code for hypersonic non-equilibrium flows. Although convergence is shown to suffer to some extent from the loosely-coupled implementation, trading a fully-coupled system for a number of smaller ones improves computational time. Furthermore, the specialized numerical discretization offers a great deal of flexibility in the implementation of numerical flux functions and boundary conditions.

Originality/value

The FEM is often disregarded in hypersonics. This paper demonstrates that this method can be used successfully for these types of flows. The present findings will be built upon in a later paper to demonstrate the powerful numerical ability of this type of solver, particularly with respect to robustness on highly stretched unstructured anisotropic grids.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 29 no. 7
Type: Research Article
ISSN: 0961-5539

Keywords

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Article
Publication date: 10 July 2009

Simona De Iulio and Carlo Vinti

The purpose of this paper is to focus on the Americanization of European advertising in the post‐war years as a phenomenon of cultural transfer and it aims to explore the…

Abstract

Purpose

The purpose of this paper is to focus on the Americanization of European advertising in the post‐war years as a phenomenon of cultural transfer and it aims to explore the interaction between the USA and Italian advertising traditions during the 1950s and the 1960s.

Design/methodology/approach

The analysis is in two parts. First, the role of those cross‐cultural mediators who contributed to changing marketing communication strategies of many Italian companies during the 1950s and the 1960s is studied. Second, the ways in which US advertising rules and patterns are combined with the local tradition in order to fit the Italian context of the post‐war years are looked at. The research is based on a study of the main USA and Italian marketing and advertising literature of the post‐war years, and on an analysis of press campaigns and TV commercials.

Findings

This research shows that during the 1950s and the 1960s, the conflict between the American approach and the Italian approach to advertising did not prevent interaction and negotiation. In the post‐war years, the USA know‐how and practices, are re‐interpreted through the process of transfer to Italy, creating original, and unexpected solutions.

Originality/value

Although some research has been conducted on the Italian advertising scene during the post‐World War II years, the few existing contributions did not focus on the interaction between the imported American model and the local traditions. This paper provides a good overview of the ways in which notions, methodologies, and strategies coming from the USA are implemented.

Details

Journal of Historical Research in Marketing, vol. 1 no. 2
Type: Research Article
ISSN: 1755-750X

Keywords

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