Исследование процесса изомеризации подсолнечного масла

В статті представлені результати дослідження процесу ізомеризації соняшникової олії. Матеріали на основі ізомеризованих олій можуть бути використані для отримання покриттів з високими фізико-механічними та захисними властивостями.In article were presented results of the study process isomerization sunflower butter. The material got on base isomerization sunflower butter, can be used for reception covering with high physico-mechanical and protective properties

Trailing Edge Noise of Wind Turbine Blades - TENwinds

Trailing edge noise is a significant contributor to the noise emissions of wind turbine blades. Thus, in this project we aim to study and understand this flow-induced noise emission with a detailed analysis of this sound source and possible mitigation strategies by employing the Lattice-Boltzmann method for a highly resolved simulation of the fluid flow and the resulting noise. We present the current status of the project - including a preliminary study consisting of wind tunnel experiments and very large eddy simulations. Based on this, the objectives for the new study are defined. A new feature that shifts the communication of the global reductions in health checks into the background, was implemented recently and it's impact is investigated in this report. We determine the setup as well as the operational parameters for production runs on Hawk to make best use of the machine

On parallel scalability aspects of strongly coupled partitioned fluid-structure-acoustics interaction

Multi-physics simulations, such as fluid-structure-acoustics interaction (FSA), require a high performance computing environment in order to perform the simulation in a reasonable amount of computation time. Currently used coupling methods use a staggered execution of the fluid and solid solver [6], which leads to inherent load imbalances. In [12] a new coupling scheme based on a quasi-Newton method is proposed for fluidstructure interaction which coupled the fluid and solid solver in parallel. The quasi- Newton method requires approximately the same number of coupling iterations per time step compared to a staggered coupling approach, resulting in a better load balance when running in a parallel environment. This contribution investigates the scalability limit and load-balancing for a strongly coupled fluid-structure interaction problem, and also for a fluid-structure-acoustics interaction problem. The acoustic far field of the fluid-structure-acoustics interaction problem is loosely coupled with the flow field

Parallel multi-scale simulations with octrees and coupled applications

Physical simulations often require the consideration of many phenomena and scales. For example in aeroacoustic problems, both, the flow generatingthe noise and the sound wave propagation needs to be considered. This work investigates numerical approaches to such problems on large distributed and parallel computing systems. The coupling framework KOP is parallelized as far as possible and to overcome fundamental scalability limits a new framework APES is developed. Both implementations utilize high-order discretizations, as these allow for accurate simulations with less degrees of freedoms than lower order methods. This property of high-order methodsis an important feature for modern supercomputing systems, as memory to represent degrees of freedom in a simulation is a scarce resource. The presented methods enable the transient simulation of multi-scale setups but detailed resolutions still require large amounts of computational resources. A focus is put on the efficient utilization of modern computing systems to address this need. Besides the scalability of the implementations, the importance of single core optimization and vectorization is illustrated. KOP uses discrete points to realize the coupling and allows for the interaction between domains with differing discretizations and solved equation systems. Arbitrary mesh configurations are supported and both, structuredand unstructured mesh solvers are available in the framework. In both framworksexplicit time integration methods are deployed to resolve the timedependent simulations. The coupling allows for a varying time step widthover the participating domains by a sub-cycling method. Various conservationlaws can be solved by the presented frameworks ranging from Maxwell’s equations and linearized Euler equations to full compressible Navier-Stokesequations. A fully distributed coupling approach is developed that allows for coupling of those in a large-scale simulation to solve, for example, aeroacousticproblems.APES enables high-order discretizations in the spectral regime. It involvesa fully scalable toolchain for mesh-based simulations featuring a meshgeneration and a post-processing tool to support the solvers. The common foundation of these tools is an Octree representation for the mesh, andthis work specifically covers the generation of high-order geometry approximationsin the developed mesh generator Seeder. This robust mechanismworks for arbitrarily complex surfaces and offers a practical way to tackleengineering tasks with spectral element discretizations

Generation of high order geometry representations in Octree meshes

We propose a robust method to convert triangulated surface data into polynomial volume data. Such polynomial representations are required for high-order partial differential solvers, as low-order surface representations would diminish the accuracy of their solution. Our proposed method deploys a first order spatial bisection algorithm to find robustly an approximation of given geometries. The resulting voxelization is then used to generate Legendre polynomials of arbitrary degree. By embedding the locally defined polynomials in cubical elements of a coarser mesh, this method can reliably approximate even complex structures, like porous media. It thereby is possible to provide appropriate material definitions for high order discontinuous Galerkin schemes. We describe the method to construct the polynomial and how it fits into the overall mesh generation. Our discussion includes numerical properties of the method and we show some results from applying it to various geometries. We have implemented the described method in our mesh generator Seeder, which is publically available under a permissive open-source license

Utilization of the Brinkman penalization to represent geometries in a high-order discontinuous Galerkin scheme on octree meshes

Finanziert aus dem DFG-geförderten Open-Access-Publikationsfonds der Universität Siegen für ZeitschriftenartikelWe investigate the suitability of the Brinkman penalization method in the context of a high-order discontinuous Galerkin scheme to represent wall boundaries in compressible flow simulations. To evaluate the accuracy of the wall model in the numerical scheme, we use setups with symmetric reflections at the wall. High-order approximations are attractive as they require few degrees of freedom to represent smooth solutions. Low memory requirements are an essential property on modern computing systems with limited memory bandwidth and capability. The high-order discretization is especially useful to represent long traveling waves, due to their small dissipation and dispersion errors. An application where this is important is the direct simulation of aeroacoustic phenomena arising from the fluid motion around obstacles. A significant problem for high-order methods is the proper definition of wall boundary conditions. The description of surfaces needs to match the discretization scheme. One option to achieve a high-order boundary description is to deform elements at the boundary into curved elements. However, creating such curved elements is delicate and prone to numerical instabilities. Immersed boundaries offer an alternative that does not require a modification of the mesh. The Brinkman penalization is such a scheme that allows us to maintain cubical elements and thereby the utilization of efficient numerical algorithms exploiting symmetry properties of the multi-dimensional basis functions. We explain the Brinkman penalization method and its application in our open-source implementation of the discontinuous Galerkin scheme, Ateles. The core of this presentation is the investigation of various penalization parameters. While we investigate the fundamental properties with one-dimensional setups, a two-dimensional reflection of an acoustic pulse at a cylinder shows how the presented method can accurately represent curved walls and maintains the symmetry of the resulting wave patterns