Kolb, Andreas
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Publication Access status: Metadata only , Decoupled Boundary Handling in SPH(2023); PArticle-based boundary representations are frequently used in smoothed pArticle hydrodynamics (SPH) due to their simple integration into fluid solvers. Commonly, incompressible fluid solvers estimate the current density and corresponding forces in case the current density exceeds the rest density to push fluid pArticles apart. Close to the boundary, the calculation of the fluid pArticles’ density involves both neighboring fluid and neighboring boundary pArticles, yielding an overestimation of density, and, subsequently, wrong pressure forces and wrong velocities leading to the disturbed fluid pArticles’ behavior in the vicinity of the boundary. In this paper, we present a detailed explanation of this disturbed fluid pArticle behavior, which is mainly due to the combined or coupled handling of the fluid–fluid pArticle and the fluid–boundary pArticle interaction. We propose the decoupled handling of both interaction types, leading to two densities for a given fluid pArticle, i.e., fluid-induced density and boundary-induced density. In our approach, we alternately apply the corresponding fluid-induced and boundary-induced forces during pressure estimation. This separation avoids force overestimation and reduces unintended fluid dynamics near the boundary, as well as a inconsistent fluid–boundary distance across different fluid amounts and different pArticle-based boundary handling methods. We compare our method with two regular state-of-the-art methods in different experiments and show how our method handles detailed boundary shapes.Source Type:Article3 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Metadata only , Evaluation of pArticle‐based smoothed pArticle hydrodynamics boundary handling approaches in computer animationBoundary handling is an important aspect of fluid simulation, and several boundary handling approaches exist in smoothed pArticle hydrodynamics (SPH), which have individual strengths and weaknesses. However, comparing different boundary handling approaches is challenging as there is no common basis for evaluations, that is, no universal set of experiments with quantitative evaluation across different methods, especially within computer animation where many evaluations rely mainly on visual perception. This Article proposes a set of experiments to aid the evaluation of the main categories of fluid‐boundary interactions that are important in computer animation, that is, no motion (resting) fluid, tangential and normal motion of a fluid with respect to the boundary, and a fluid impacting a corner . We propose ten experiments, comprising experimental setup and quantitative evaluation with optional visual inspections, that are arranged in four groups which focus on one of the main category of fluid‐boundary interactions. We use these experiments to evaluate three pArticle‐based boundary handling methods, that is, pressure mirroring, pressure boundaries, and moving least squares pressure extrapolation, in combination with two incompressible SPH fluid simulation methods, namely IISPH and DFSPH, to establish a quantifiable relation between different combinations of boundary handling with simulation approaches and the main categories of fluid‐boundary interactions. Finally, we summarize all results in a rating table and show how our experiments can be used to determine the promising method for specific requirements regarding a given constellation of fluid‐boundary interaction.Source Type:ArticleDOI:10.1002/cav.21383 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Metadata only , Pacemod: parametric contour-based modifications for glyph generation(2023); ; Metaphoric glyphs are intuitively related to the underlying problem domain and enhance the readability and learnability of the resulting visualization. Their construction, however, implies an appropriate modification of the base icon, which is a predominantly manual process. In this paper, we introduce the parametric contour-based modification (PACEMOD) approach that lays the foundations of automated, controllable icon manipulations. Technically, the PACEMOD parametric representation utilizes diffusion curves, enriched with new degrees of freedom in arc-length parameterization, which allows for manipulation of the icon contours’ geometry and the related color attributes. Moreover, we propose an implementation of our generic approach for a specific, automated design of metaphoric glyphs, based on periodic, wave-like contour modifications. Finally, the practicality of such periodic contour modifications is demonstrated by two visualization examples, which comprise uncertainty visualization of a rain forecast and gradient glyphs applied to COVID-19 data. In summary, with the PACEMOD approach we introduce an instrument that facilitates a user-centered design of metaphoric glyphs and provides a generic basis for potential further implementations according to specific applications.Source Type:Article3