In einer Einleitung werden verschiedene Möglichkeiten der Kopplung unterschiedlicher physikalischer Domänen diskutiert. Begriffe wie Kopplung auf Systemebene über Terminals und auf Feldebene über Lastvektor oder Matrixkopplung werden zugeordnet. Wie diese Kopplungsmöglichkeiten sich in der ANSYS Simulationsumgebung wiederfinden, wird aufgezeigt. Am Beispiel eines Akuators wird erläutert, welche physikalischen Domänen gekoppelt betrachtet werden müssen, um die hier vorhandenen temperaturabhängigen Materialeigenschaften zu berücksichtigen. In einem Beispiel zu einer Steckverbindung wird aufgezeigt, wie eine vom Kontaktdruck abhängige Leitfähigkeit berücksichtigt wird und Ergebnisse aus dieser Simulation werden diskutiert.

Die Verarbeitung von Folien auf Schneid und Wickelmaschinen erzeugt je nach verwendetem Material Schneidstaubpartikel, welche die Produktqualität herabsetzen können. Um eine hohe Qualität sicherzustellen, wird der Schneidstaub in unmittelbarer Nähe zu seiner Entstehung durch spezielle Absaugungsvorrichtungen entfernt. Versuche haben jedoch gezeigt, dass trotz hoher Absaugleistung bei bestimmten Prozessparametern ein Teil der Partikel nicht erfasst wird. Daher wird im Anschluss an eine Erhebung der bestehenden Systemgrößen ein Modell der Absaugdüse mittels numerischer Simulation auf ihre Eignung zur Partikelentfernung untersucht. Die Untersuchung zeigt, dass bei der Auslegung der Düse eine Berücksichtigung der auf der Folie entstehenden Grenzschicht zwingend erforderlich ist. Um eine zuverlässige Absaugung aller Schneidstaubpartikel auch bei extremen Prozesseinstellungen sicherzustellen, werden weitere Untersuchungen und Anpassungen erforderlich.

In diesem Beitrag wird die Wirksamkeit statischer Mischer in verschiedenen Anordnungen und Strömungskonfigurationen untersucht. Auf Grundlage umfangreicher numerischer Untersuchungen werden die Anwendungsgrenzen von spiralförmigen statischen Mischern zur Verbesserung des Wärmeübergangs in Kühlkanälen von Werkzeugmaschinen aufgezeigt. Die numerischen Simulationen wurden mit der kommerziellen Computational-Fluid-Dynamics (CFD)-Software, ANSYS Fluent 2020 R2, durchgeführt. Diese Studie zeigt, dass es einen optimalen Anwendungsbereich für statische Mischer als Wärmeaustauschverstärker in Abhängigkeit von der Strömungsgeschwindigkeit, dem übertragenen Wärmestrom und der Wärmeleitfähigkeit des Werkzeugs gibt. Die Untersuchungen in diesem Beitrag beschränken sich auf einphasige Strömungen in kreisförmigen Querschnitten und geraden Kanalgeometrien. Als repräsentatives Anwendungsbeispiel für eine Werkzeugmaschine wird die Kühlung eines einfachen Spritzgießwerkzeugs untersucht. Die durchgeführten Analysen zeigen, dass der Einsatz von statischer Mischelemente zur Verbesserung der Wärmeübertragung sehr effektiv ist, insbesondere bei Strömungen mit niedrigen bis mittleren Reynoldszahlen, konturnaher Kühlung, hohen Wärmestromwerten sowie hoher Wärmeleitfähigkeit des Werkzeugmaterials. / In this contribution, the effectiveness of helical static mixers in different arrangements and flow configurations/regimes is explored. By means of a thorough numerical analysis the application limits of helical static mixers for the heat transfer enhancement inside cooling channels of machine tools is provided. The numerical simulations were processed with the commercial finite volume Computational Fluid Dynamics (CFD) code, ANSYS Fluent 2020 R2. This study shows that there exists an optimal range of application for static mixers as heat exchange intensifier depending on the flow speed, the transmitted heat flow and the thermal conductivity of the tool. The investigations of this contribution are restricted to single-phase flow in circular cross-sections and straight channel geometries. As a representative application example for a machine tooling, the cooling of a simple injection mould is investigated. The research carried out reveals that the application of static mixing elements for enhancement of heat transfer is very effective, particularly for fluid flow with low to medium Reynolds numbers, close-contour cooling, high values of heat fluxes as well as high thermal conductivity of the tooling material.

‘Coupled process’ implies that one process affects the initiation and progress of the others and vice versa. The deformation and damage behaviors of rock under loading process change the fluid flow field within it, and lead to altering in permeable characteristics; on the other side inner fluid flow leads to altering in pore pressure and effective stress of rock matrix and flow by influencing stress strain behavior of rock. Therefore, responses of rock to natural or man-made perturbations cannot be predicted with confidence by considering each process independently. As far as hydro-mechanical behavior of rock is concerned, the researchers have always been making efforts to develop the model which can represent the permeable characteristics as well as stress-strain behaviors during the entire damage process. A brittle low porous granite was chosen as the study object in this thesis, the aim is to establish a corresponding constitutive law including the relation between permeability evolution and mechanical deformation as well as the rock failure behavior under hydro-mechanical coupled conditions based on own hydro-mechanical coupled lab tests. The main research works of this thesis are as follows: 1. The fluid flow and mechanical theoretical models have been reviewed and the theoretical methods to solve hydro-mechanical coupled problems of porous medium such as flow equations, elasto-plastic constitutive law, and Biot coupled control equations have been summarized. 2. A series of laboratory tests have been conducted on the granite from Erzgebirge–Vogtland region within the Saxothuringian segment of Central Europe, including: permeability measurements, ultrasonic wave speed measurements, Brazilian tests, uniaxial and triaxial compression tests. A hydro-mechanical coupled testing system has been designed and used to conduct drained, undrained triaxial compression tests and permeability evolution measurements during complete loading process. A set of physical and mechanical parameters were obtained. 3. Based on analyzing the complete stress-strain curves obtained from triaxial compression tests and Hoek-Brown failure criterion, a modified elemental elasto-plastic constitutive law was developed which can represent strength degradation and volume dilation considering the influence of confining pressure. 4. The mechanism of HM-coupled behavior according to the Biot theory of elastic porous medium is summarized. A trilinear evolution rule for Biot’s coefficient based on the laboratory observations was deduced to eliminate the error in predicting rock strength caused by constant Biot’s coefficient. 5. The permeability evolution of low porous rock during the failure process was described based on literature data and own measurements, a general rule for the permeability evolution was developed for the laboratory scale, a strong linear relation between permeability and volumetrical strain was observed and a linear function was extracted to predict permeability evolution during loading process based on own measurements. 6. By combining modified constitutive law, the trilinear Biot’s coefficient evolution model and the linear relationship between permeability and volumetrical strain, a fully hydro-mechanical coupled numerical simulation scheme was developed and implemented in FLAC3D. A series of numerical simulations of triaxial compression test considering the hydro-mechanical coupling were performed with FLAC3D. And a good agreement was found between the numerical simulation results and the laboratory measurements under 20 MPa confining pressure and 10 MPa fluid pressure, the feasibility of this fully hydro-mechanical coupled model was proven.

This thesis documents the development of a simulation strategy to model the behavior of geomembranes at large deformations using the explicit finite difference code FLAC3D. The geomembrane is represented by special shell elements and interfaces at both sides of the geomembrane duplicating the interaction with the overlying and underlying materials. Chapter 1 provides an introduction to geotextiles and geomembranes, and their use in geotechnical engineering. Special attention is paid to pull-out tests because of their importance to describe the behavior at large deformations. Chapter 2 describes the proposed ‘liner’ model concept to simulate the interaction of a geomembrane with the over- and underlying material. Furthermore, this chapter documents in detail the simulation of uniaxial pull-out tests for validation of the proposed ‘liner’ model concept and compares it with the FLAC3D built-in geogrid element. To clarify more clearly the potential failure (crack propagation and rupture process) of the geomembrane, the ‘liner’ model under biaxial loading was investigated in Chapter 3. Chapter 4 documents a detailed parameter study with a special focus on the stiffness and frictional behavior of the ‘liner’ element using a simplified waste dump. In chapter 5 a new constitutive model (“Femesalz”) is proposed to describe the visco-elasto-plastic behavior of crushed salt and waste rock salt, respectively. The “Femesalz” constitutive model together with the ‘liner’ model is applied to simulate the behavior of a rock salt waste dump (2.5-dimensional) to validate both, the new constitutive model “Femesalz” as well as the ‘liner’ model. Chapter 6 documents the use of the ‘liner’ element and the “Femesalz” constitutive model to simulate salt dump models in 2D and 3D on different terrain types (mountain, valley, plain) for a time of 100 years to generate large deformations. Chapter 7 contains the main conclusions and recommendations.:ABSTRACT AND STRUCTURE OF THESIS 2 ACKNOWLEDGMENTS 4 CONTENTS 5 LIST OF TABLES 7 LIST OF FIGURES 10 NOMENCLATURE 16 CHAPTER 1: INTRODUCTION AND STATE-OF-THE-ART 22 1.1 Geosynthetic for geoengineering projects (overview) 22 1.2 Pull-out tests (overview) 29 CHAPTER 2: “LINER” CONCEPT AND NUMERICAL SIMULATIONS OF UNIAXIAL PULL-OUT TESTS 39 2.1 Introduction 39 2.2 Numerical calculations 39 2.2.1 General considerations 39 2.2.2 Concept of the 'liner' element 40 2.2.3 'Geogrid' versus 'liner' element 41 2.2.4 Verification of ‘liner’ element 42 2.2.5 Conclusions 58 CHAPTER 3: BIAXIAL LOADING OF “LINER” MODEL 61 3.1 Introduction 61 3.2 Model set-up 61 3.3 Results of biaxial pull-out test simulation 63 3.4 Summary and Conclusions 71 CHAPTER 4: PARAMETER STUDY OF EMBEDDED GEOMEMBRANE 74 4.1 Introduction 74 4.2 Model set-up 74 4.3 Results 77 4.3.1 Influence of interface stiffness 80 4.3.2 Influence of interface friction 87 4.4 Conclusions 93 CHAPTER 5: CONSTITUTIVE MODEL FOR SALT DUMP 95 5.1 Introduction 95 5.1.1 Overview of constitutive models for rock salt 97 5.1.2 Overview of constitutive models for crushed salt 104 5.2 ‘Femesalz’ constitutive model for crushed salt 106 5.2.1 Introduction 106 5.2.2 Compaction test 111 5.2.3 Triaxial test and realistic waste dump simulation 114 5.2.4 Numerical salt dump simulations 115 5.3 Summary 122 CHAPTER 6: SIMULATIONS CONSIDERING TOPOGRAPHY OF UNDERLYING MATERIAL 123 6.1 Introduction 123 6.2 Model set-up 123 6.3 Model parameters and calculation sequence 131 6.4 Calculation results 132 6.5 Discussion of results and conclusions 139 CHAPTER 7: CONCLUSIONS 141 REFERENCE 143

The article describes direct numerical simulations using an Euler–Lagrange approach with an immersed-boundary method to resolve the geometry and trajectory of particles moving in a flow. The presentation focuses on own work of the authors and discusses elements of physical and numerical modeling in some detail, together with three areas of application: microfluidic transport of spherical and nonspherical particles in curved ducts, flows with bubbles at different void fraction ranging from single bubbles to dense particle clusters, some also subjected to electro-magnetic forces, and bedload sediment transport with spherical and nonspherical particles. These applications with their specific requirements for numerical modeling illustrate the versatility of the approach and provide condensed information about main findings.

Galvanic corrosion is a destructive process between dissimilar metals. The present paper presents a constructed numerical test case to simulate galvanic corrosion of two dissimilar metals. This test case is used to study the accuracy of different implementations to track the dissolving anode boundary. One technique is to numerically simulate a mesh displacement based on the prescribed displacement at the anode boundary. The second method is to adjust only the boundary elements. Re-meshing after a certain number of time steps is applied to both implementations. They produce similar results for an electrical and electrochemical field problem. This work shows that mesh smoothing does not result in higher accuracy when modeling a moving anode front. Adjusting only the boundary elements is sufficient when frequent re-meshing is used.

Histological slides are an important tool in the diagnosis of tumors as well as of other diseases that affect cell shapes and distributions. Until now, the research concerning an optimal staining time has been mainly done empirically. In experimental investigations, it is often not possible to stain an already-stained slide with another stain to receive further information. To overcome these challenges, in the present paper a continuum-based model was developed for conducting a virtual (re-)staining of a scanned histological slide. This model is capable of simulating the staining of cell nuclei with the dye hematoxylin (C.I. 75,290). The transport and binding of the dye are modeled (i) along with the resulting RGB intensities (ii). For (i), a coupled diffusion–reaction equation is used and for (ii) Beer–Lambert’s law. For the spatial discretization an approach based on the finite element method (FEM) is used and for the time discretization a finite difference method (FDM). For the validation of the proposed model, frozen sections from human liver biopsies stained with hemalum were used. The staining times were varied so that the development of the staining intensity could be observed over time. The results show that the model is capable of predicting the staining process. The model can therefore be used to perform a virtual (re-)staining of a histological sample. This allows a change of the staining parameters without the need of acquiring an additional sample. The virtual standardization of the staining is the first step towards universal cross-site comparability of histological slides.

Bei der Druckabsicherung von verfahrenstechnischen Anlagen spielen Berstscheiben eine entscheidende Rolle. Sie reagieren auf kritische Druckänderungen im zu schützenden System und geben ihren Entlastungsquerschnitt bei Bedarf vollständig frei. Als drucktragende Komponente einer Berstscheibe muss die Berstmembran die regulären Betriebsbelastungen des abzusichernden Prozesses zuverlässig abtragen und darf erst bei Erreichen einer kritischen Druckbelastung ansprechen. Aufgrund ihres guten Tragverhaltens bieten Berstscheiben mit vorgewölbter Berstmembran ein breites Einsatzspektrum. Während des Fertigungsprozesses von vorgewölbten Berstscheiben wird eine anfänglich flache Blechronde über einen Aeroforming- Prozess zu einer Berstmembran mit annähernd sphärischer Gestalt geformt. Dieser plastische Deformationsprozess wird über eine numerische Simulation mittels Finite-Elemente-Methode beschrieben und die dabei wirkenden Zusammenhänge aufgezeigt. Die Simulation wird zudem durch experimentelle Versuche begleitet und validiert. / Rupture discs play an essential role in the pressure protection of process engineering systems. They react to critical pressure changes in the system to be protected and fully release their relief cross-section as required. As the pressure-bearing component of a rupture disc, the rupture diaphragm must reliably withstand the regular operating loads of the process to be protected and may only respond when a critical pressure load is reached. Due to their good load- bearing behavior, rupture discs with pre-domed rupture diaphragms offer a wide range of applications. During the manufacturing process of pre-domed rupture discs, an initially flat sheet metal blank is formed into a rupture diaphragm with an approximately spherical shape using an aeroforming process. This plastic deformation process is described by a numerical simulation using the finite element method and the relationships involved are shown. The simulation is also accompanied and validated by experimental tests.

Mit der Fuzzy-Stochastischen Finite-Elemente-Methode (FSFEM) kann die nachgewiesene stochastische und nichtstochastische Datenunschärfe des stahlbewehrten Altbetons und des Textilbeton bei der Strukturanalyse berücksichtigt werden. Die für die deterministische Analyse textilverstärkter Tragwerke auf der Basis des Multi-Referenzebenen-Modells (MRM) entwickelten finiten MRM-Elemente wurden zu FSMRM-Elementen weiterentwickelt. Das Stoffmodell des mit AR-Glas bewehrten Feinbetons wurde für textile Gelege aus Carbon erweitert. Die entwickelten Modelle und Algorithmen werden zur fuzzystochastischen Tragwerksanalyse textilverstärkter Tragwerke eingesetzt.