High-resolution Numerical Analysis of Flow over a Ground Sill Using OpenFOAM

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchive

CFD-modelling of free surface flows in closed conduits

[EN] Computational fluid dynamics (CFD) is gaining an increasing importance in the field of hydraulic engineering. This publication presents different application examples of a two-phase approach as implemented in the open source software OpenFOAM. The chosen approach is based on the volume of fluid method focusing on the simulation of flow in closed conduits. Three examples are presented: single-phase flow over a ground sill and free surface flow over a hill as well as complex free surface flow in a sewer model. The first example compares the results of different RANS turbulence models with experimental results. The results of the second example are compared with an analytical solution. In the last example the behaviour of the free surface flow is compared with the results of a model test and existing simulations using a simplified, open channel geometry for the closed conduit. For the examples analysed, the two-phase approach provides stable and reliable resultsThe funding provided by the German Research Foundation (DFG) within the Research Training Group ‘Urban Water Interfaces’ (GRK 2032) is gratefully acknowledged.Teuber, K.; Broecker, T.; Bayón, A.; Nutzmann, G.; Hinkelmann, R. (2019). CFD-modelling of free surface flows in closed conduits. Progress in Computational Fluid Dynamics An International Journal. 19(6):368-380. http://hdl.handle.net/10251/128737S36838019

Integral Flow Modelling Approach for Surface Water-Groundwater Interactions along a Rippled Streambed

Exchange processes of surface and groundwater are important for the management of water quantity and quality as well as for the ecological functioning. In contrast to most numerical simulations using coupled models to investigate these processes, we present a novel integral formulation for the sediment-water-interface. The computational fluid dynamics (CFD) model OpenFOAM was used to solve an extended version of the three-dimensional Navier–Stokes equations which is also applicable in non-Darcy-flow layers. Simulations were conducted to determine the influence of ripple morphologies and surface hydraulics on the flow processes within the hyporheic zone for a sandy and for a gravel sediment. In- and outflowing exchange fluxes along a ripple were determined for each case. The results indicate that larger grain size diameters, as well as ripple distances, increased hyporheic exchange fluxes significantly. For higher ripple dimensions, no clear relationship to hyporheic exchange was found. Larger ripple lengths decreased the hyporheic exchange fluxes due to less turbulence between the ripples. For all cases with sand, non-Darcy-flow was observed at an upper layer of the ripple, whereas for gravel non-Darcy-flow was recognized nearly down to the bottom boundary. Moreover, the sediment grain sizes influenced also the surface water flow significantly.Deutsche ForschungsgemeinschaftPeer Reviewe

Genetic factors influencing a neurobiological substrate for psychiatric disorders

A retrospective meta-analysis of magnetic resonance imaging voxel-based morphometry studies proposed that reduced gray matter volumes in the dorsal anterior cingulate and the left and right anterior insular cortex-areas that constitute hub nodes of the salience network-represent a common substrate for major psychiatric disorders. Here, we investigated the hypothesis that the common substrate serves as an intermediate phenotype to detect genetic risk variants relevant for psychiatric disease. To this end, after a data reduction step, we conducted genome-wide association studies of a combined common substrate measure in four population-based cohorts (n = 2271), followed by meta-analysis and replication in a fifth cohort (n = 865). After correction for covariates, the heritability of the common substrate was estimated at 0.50 (standard error 0.18). The top single-nucleotide polymorphism (SNP) rs17076061 was associated with the common substrate at genome-wide significance and replicated, explaining 1.2% of the common substrate variance. This SNP mapped to a locus on chromosome 5q35.2 harboring genes involved in neuronal development and regeneration. In follow-up analyses, rs17076061 was not robustly associated with psychiatric disease, and no overlap was found between the broader genetic architecture of the common substrate and genetic risk for major depressive disorder, bipolar disorder, or schizophrenia. In conclusion, our study identified that common genetic variation indeed influences the common substrate, but that these variants do not directly translate to increased disease risk. Future studies should investigate gene-by-environment interactions and employ functional imaging to understand how salience network structure translates to psychiatric disorder risk

Ein dreidimensionales Zweiphasenmodell für Strömung, Transport und Massentransfer im Kanal

Sewer networks are one major pillar of modern cities’ infrastructure. Their functionality ensures the transport of wastewater to the sewage treatment plant and the transport of rainwater from residential areas. Damages to sewers cause infiltration and exfiltration and at the same time high costs for rehabilitation. The formation of hydrogen sulphide (H2S) represents a risk factor for the conditions of concrete channels. Its emission cannot only cause the destruction of sewer walls by concrete corrosion, but can also represent a safety risk for sewer workers. Within the last decades, the characteristics of H2S emissions were intensively investigated and various models for predicting odour and corrosion were developed. The current state of the art are one-dimensional model approaches. At the same time, some predominant processes, e.g. the flow velocities in the air phase, are three-dimensional, and H2S emissions are very relevant on locations with high turbulence and complex flow fields (e.g. drops). This work continues at this point. It investigates and extends a three-dimensional twophase model with regard to different aspects. For this purpose the two-phase solver interFoam of the software OpenFOAM is used. Initially, the hydrodynamic properties for different models in closed conduits are investigated by analysing hydrodynamic properties for different models in closed cross sections. The analysis begins with the simulation of a simple single-phase water flow over a ground sill and is then extended to a highly complex sewer geometry. The complex sewer network geometry is compared with results of a 1:20 scale model and existing CFD simulations for an open geometry. The results show a good agreement. Extensions are based on the description of mass transfer using the Henry coefficient. Furthermore, adjustments are made to improve the specifics of H2S emissions in sewers. These include the description of the temperature dependency of the Henry coefficient, the equilibrium between H2S and the bisulphide ion (HS-) in the water phase and the influence of the pH value on this equilibrium. An additional extension describes the concentration of H2S in the air phase as partial pressure. The extensions and adaptations are validated using different analytical examples and the advantages of using a three-dimensional model over a one-dimensional approach are demonstrated using the example of the complex sewer geometry. Finally, the extended solver is coupled with a solver for dynamic geometries to validate the simulated mass transfer under turbulent conditions. The comparison of simulation results for mass transfer in a stirring tank with different stirring rates leads to a good agreement with experimental results from laboratory experiments. This work results in two new solvers, the difference of which lies in the geometry to be described. The first solver can be applied to static meshes, while the second solver can describe dynamic meshes, such as rotating geometries.Kanalnetze stellen eine wichtige Säule in der Infrastruktur moderner Städte dar. Ihre Funktionsfähigkeit sichert den Transport von Abwasser zur Kläranlage und den Transport von Regenwasser aus Siedlungsgebieten. Schäden an Kanälen können zu In- und Exfiltrationen und gleichzeitig hohen Instandsetzungskosten führen. Einen Risikofaktor für den Zustand von Betonkanälen stellen Umwandlungsprozesse von Schwefelwasserstoff (H2S) dar. Ihre Emission kann nicht nur Kanalwände durch Betonkorrosion zerstören, sondern auch ein Sicherheitsrisiko für Kanalarbeiter*innen darstellen. Innerhalb der letzten Dekaden wurden H2S Emissionen intensiv erforscht und verschiedenste Modelle zur Vorhersage von Geruch und Korrosion entwickelt. Der aktuelle Stand der Technik sind eindimensionalle Modellansätze. Gleichzeitig sind einige vorherrschende Prozesse, beispielsweise die Fließgeschwindigkeiten in der Luftphase, dreidimensional und H2S Emissionen spielen eine besondere Rolle an Stellen mit hoher Turbulenz und komplexen Strömungsfeldern (z.B. Abstürze). Diese Arbeit setzt an diesem Punkt an und untersucht und erweitert ein dreidimensionales Zweiphasenmodell hinsichtlich unterschiedlicher Aspekte. Hierfür wird der Zweiphasen- Löser interFoam der Software OpenFOAM verwendet. In einem ersten Schritt werden die hydrodynamischen Eigenschaften für unterschiedliche Modelle in geschlossenen Querschnitten untersucht. Die Testfälle beginnen bei der einfachen Simulation einer Einphasen-Wasserströmung über eine Schwelle und werden dann hin zu einer hochkomplexen Kanalnetzgeometrie erweitert. Die Ergebnisse der Simulationen werden mit experimentellen Ergebnissen und analytischen Lösungen verglichen. Die komplexe Kanalnetzgeometrie wird mit Ergebnissen eines im Verhältnis 1:20 gebauten Modellversuchs und mit existierenden CFDSimulationen für eine offene Geometrie verglichen, und die Ergebnisse zeigen eine gute Übereinstimmung. Es werden Transport-und Massentransferprozesse anhand verschiedener Beispiele untersucht, wozu vorhandene Erweiterungen des Lösers verwendet werden. Diese Erweiterungen basieren auf der Beschreibung von Massentransfer mittels des Henry- Koeffizienten. Es werden Anpassungen vorgenommen, um H2S Emissionen im Kanal besser beschreiben zu können. Diese umfassen die Beschreibung der Temperaturabhängigkeit des Henry-Koeffizienten sowie das Gleichgewicht zwischen H2S und dem Hydrogensulfid- Anion (HS-) in der Wasserphase und den Einfluss des pH Wertes auf dieses Gleichgewicht. Eine zusätzliche Erweiterung beschreibt die Konzentration von H2S in der Luftphase als Partialdruck. Die Erweiterungen und Anpassungen werden anhand unterschiedlicher analytischer Beispiele validiert, und es werden die Vorteile der Anwendung eines dreidimensionalen Modells gegenüber eines eindimensionalen Ansatzes wird am Beispiel der komplexen Kanalgeometrie gezeigt. Zuletzt wird der erweiterte Löser mit einem Löser für dynamische Geometrien gekoppelt, um den simulierten Massentransfer unter turbulenten Bedingungen zu validieren. Der Vergleich von Simulationsergebnissen für Massentransfer in einem Rührbehälter mit unterschiedlichen Rührgeschwindigkeiten führt zu einer guten Übereinstimmung mit experimentellen Ergebnissen aus Laborversuchen. Insgesamt resultieren aus der Arbeit zwei neue Löser, deren Unterschied in der zu beschreibenden Geometrie liegt. Der erste Löser kann im Bereich von statischen Netzen angewandt werden, während der zweite Löser dynamische Geometrien, wie zum Beispiel die Bewegung von Rotoren, beschreiben kann.DFG, GRK 2032/1, Grenzzonen in urbanen Wassersysteme

Coarse Grid Strategies for Computationally Efficient Flash Flood Simulations

The Second International Symposium on Flash Floods in Wadi Systems: 25-27 October 2016. Technische Universität Berlin, Campus El Gouna, Egypt

Combined Cytotoxic And Anti-Invasive Properties Of Redox-Active Nanoparticles In Tumor-Stroma Interactions

Tumor-stroma interaction plays an important role in tumor progression. Myofibroblasts, pivotal for tumor progression, populate the microecosystem of reactive stroma. The formation of myofibroblasts is mediated by tumor derived transforming growth factor β1 (TGFβ1) which initiates a reactive oxygen species cell type dependent expression of alpha-smooth muscle actin, a biomarker for myofibroblastic cells. Myofibroblasts express and secrete proinvasive factors significantly increasing the invasive capacity of tumor cells via paracrine mechanisms. Although antioxidants prevent myofibroblast formation, the same antioxidants increase the aggressive behavior of the tumor cells. In this study, the question was addressed of whether redox-active polymer-coated cerium oxide nanoparticles (CNP, nanoceria) affect myofibroblast formation, cell toxicity, and tumor invasion. Herein, nanoceria downregulate both the expression of alpha-smooth muscle actin positive myofibroblastic cells and the invasion of tumor cells. Furthermore, concentrations of nanoceria being non-toxic for normal (stromal) cells show a cytotoxic effect on squamous tumor cells. The treatment with redox-active CNP may form the basis for protection of stromal cells from the dominating influence of tumor cells in tumor-stroma interaction, thus being a promising strategy for chemoprevention of tumor invasion. © 2011 Elsevier Ltd

Web-basierte Plattform zur Betriebsoptimierung von Wassersystemen

Mit W-Net 4.0 wird eine modulare und skalierbare Plattform entwickelt, die GIS-System, Simulationssoftware, Datenanalyse-Tools und hohe IT-Sicherheitsstandards vereint. Versorger können neue Datenanalyse- und Optimierungswerkzeuge, Dienstleistungs- und Schulungskonzepte nutzen

Symposium: Außerschulische Bildungsangebote – Bedingungen der Inanspruchnahme und Wirkungen

Teuber Z, Wild E, Entrich SR, et al. Symposium: Außerschulische Bildungsangebote – Bedingungen der Inanspruchnahme und Wirkungen. Presented at the PAEPSY - Tagung der Fachgruppe Pädagogischer Psychologie, Heideberg