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- Delorme, Yann T., et al.
(författare)
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A simple and efficient incompressible Navier-Stokes solver for unsteady complex geometry flows on truncated domains
- 2017
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Ingår i: Computers & Fluids. - : Elsevier. - 0045-7930 .- 1879-0747. ; 150, s. 84-94
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Tidskriftsartikel (refereegranskat)abstract
- Incompressible Navier-Stokes solvers based on the projection method often require an expensive numerical solution of a Poisson equation for a pressure-like variable. This often involves linear system solvers based on iterative and multigrid methods which may limit the ability to scale to large numbers of processors. The artificial compressibility method (ACM) [6] introduces a time derivative of the pressure into the incompressible form of the continuity equation creating a coupled closed hyperbolic system that does not require a Poisson equation solution and allows for explicit time-marching and localized stencil numerical methods. Such a scheme should theoretically scale well on large numbers of CPUs, GPU'€™s, or hybrid CPU-GPU architectures. The original ACM was only valid for steady flows and dual-time stepping was often used for time-accurate simulations. Recently, Clausen [7] has proposed the entropically damped artificial compressibility (EDAC) method which is applicable to both steady and unsteady flows without the need for dual-time stepping. The EDAC scheme was successfully tested with both a finite-difference MacCormack'€™s method for the two-dimensional lid driven cavity and periodic double shear layer problem and a finite-element method for flow over a square cylinder, with scaling studies on the latter to large numbers of processors. In this study, we discretize the EDAC formulation with a new optimized high-order centered finite-difference scheme and an explicit fourth-order Runge-€“Kutta method. This is combined with an immersed boundary method to efficiently treat complex geometries and a new robust outflow boundary condition to enable higher Reynolds number simulations on truncated domains. Validation studies for the Taylor-€“Green Vortex problem and the lid driven cavity problem in both 2D and 3D are presented. An eddy viscosity subgrid-scale model is used to enable large eddy simulations for the 3D cases. Finally, an application to flow over a sphere is presented to highlight the boundary condition and performance comparisons to a traditional incompressible Navier-€“Stokes solver is shown for the 3D lid driven cavity. Overall, the combined EDAC formulation and discretization is shown to be both effective and affordable.
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| 2. |
- Hornborg, Anne-Christine, et al.
(författare)
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Rites for Modern Man: New Practices in Sweden
- 2007
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Ingår i: The Ritual Year and Ritual Diversity: Proceedings of the second International Conference of the SIEF Working Group on the Ritual Year, Gothenburg June 7-11, 2006. - Göteborg : Institutet för språk och folkminnen ;Göteborg :Dialekt-, ortnamns- och folkminnesarkivet i Göteborg. - 9789172290396 ; , s. 83-92
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Bokkapitel (refereegranskat)abstract
- This article offers a new perspective on the use of ritual and tradition in contemporary Sweden. Urbanization, immigration, cultural pluralism, the capitalist market system, changing conditions for women, the influence of mass media, and individualism are all characteristic of the social condition of modernity that have radically changed the context of ritual and transformed traditional patterns. New rituals or ritualized practices have emerged that respond to these contemporary societal structures. It presents some of these practices, discusses different categories of new ritual mastery and investigates the increasing demand from the participants for efficacy and personal meaning in rituals. Finally, it raises the delicate question whether it is justifiable, or even desirable, to maintain a critical stance to these features of modernity.
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