Pooyan Dadvand

Open tools for electromagnetic simulation programs

Purpose – The aim of the paper is to propose three computer tools to create electromagnetic simulation programs: GiD, Kratos and EMANT.Design/methodology/approach – The paper presents a review of numerical methods for solving electromagnetic problems and presentation of the main features of GiD, Kratos and EMANT.Findings – The paper provides information about three computer tools to create electromagnetic simulation packages: GiD (geometrical modeling, data input, visualisation of results), Kratos (C++ library) and EMANT (finite element software for solving Maxwell equations).Research limitations/implications – The proposed platforms are in development and future work should be done to validate the codes for expecific problems and to provide extensive manual and tutorial information.Practical implications – The tools could be easily learnt by different user profiles: from end‐users interested in simulation programs to developers of simulation packages.Originality/value – This paper offers an integrated vi...

A robust algorithm for implicit description of immersed geometries within a background mesh

The paper presents a robust algorithm, which allows to implicitly describe and track immersed geometries within a background mesh. The background mesh is assumed to be unstructured and discretized by tetrahedrons. The contained geometry is assumed to be given as triangulated surface. Within the background mesh, the immersed geometry is described implicitly using a discontinuous distance function based on a level-set approach. This distance function allows to consider both, “double-sided” geometries like membrane or shell structures, and “single-sided” objects for which an enclosed volume is univocally defined. For the second case, the discontinuous distance function is complemented by a continuous signed distance function, whereas ray casting is applied to identify the closed volume regions. Furthermore, adaptive mesh refinement is employed to provide the necessary resolution of the background mesh. The proposed algorithm can handle arbitrarily complicated geometries, possibly containing modeling errors (i.e., gaps, overlaps or a non-unique orientation of surface normals). Another important advantage of the algorithm is the embarrassingly parallel nature of its operations. This characteristic allows for a straightforward parallelization using MPI. All developments were implemented within the open source framework “KratosMultiphysics” and are available under the BSD license. The capabilities of the implementation are demonstrated with various application examples involving practice-oriented geometries. The results finally show, that the algorithm is able to describe most complicated geometries within a background mesh, whereas the approximation quality may be directly controlled by mesh refinement.

Contribution to the Fluid-Structure Interaction Analysis of Ultra-Lightweight Structures using an Embedded Approach

Designing large ultra-lightweight structures within a fluid flow, such as inflatable hangars in an atmospheric environment, requires an analysis of the naturally occurring fluid-structure interaction (FSI). To this end multidisciplinary simulation techniques may be used. The latter, though, have to be capable of dealing with complex shapes and large deformations as well as challenging phenomena like wrinkling or folding of the structure. To overcome such problems the method of embedded domains may be used. In this work we discuss a new solution procedure for FSI analyses based on the method of embedded domains. In doing so, we are in particular answering the questions: How to track the interface in the embedded approach, how does the subsequent solution procedure look like and how does both compare to the well-known Arbitrary-Lagrangian-Eulerian (ALE) approach? In this context a level set technique as well as different mapping and mesh-updating strategies are developed and evaluated. Furthermore the solution procedure of a completely embedded FSI analysis is established and tested using different small- and large-scale examples. All results are finally compared to results from an ALE approach. It is shown that the embedded approach offers a powerful and robust alternative in terms of the FSI analysis of ultra-lightweight structures with complex shapes and large deformations. With regard to the solution accuracy, however, clear restrictions are elaborated.

From Large Scale to Cloud Computing

In migration of the complete pipeline of the simulation we found out several similarities with large scale computing. Our perspective of cloud computing was for many small to medium calculations, however we found out that many developments are similar to the ones for large scale computing. In this presentation we describe such similarities and point out how they affect in our development in both lines.

On the application of two-fluid flows solver to the casting problem

Two-fluid modeling of the casting process is important as it particularly provides insight to the air behavior during the filling process. Large deformations of the material-air front require an interface capturing technique to detect it on the fixed Eulerian meshes. On the other hand, if sharp interface is considered, jumps in the material properties along one single element causes severe instabilities in the solution. We review various techniques developed for both conservative level set method to capture the interface, and enrichment techniques to cure the instabilities. The coupling of the level set method with one of these enrichment techniques is applied to the mold filling process.