The compressible granular collapse in a fluid as a continuum: validity of a Navier-Stokes model with μ(J)\mu(J)-ϕ(J)\phi(J)-rheology

The incompressible $\mu(I)$-rheology has been used to study subaerial granular flows with remarkable success. For subaquatic granular flows, drag between grains and the pore fluid is substantially higher and the physical behaviour is more complex. High drag forces constrain the rearrangement of grains and dilatancy, leading to a considerable build-up of pore pressure. Its transient and dynamic description is the key to modelling subaquatic granular flows but out of the scope of incompressible models. In this work, we advance from the incompressible $\mu(I)$-rheology to the compressible $\mu(J)$-$\phi(J)$-rheology to account for pore pressure, dilatancy, and the scaling laws under subaquatic conditions. The model is supplemented with critical state theory to yield the correct properties in the quasi-static limit. The pore fluid is described by an additional set of conservation equations and the interaction with grains is described by a drag model. This new implementation enables us to include most of the physical processes relevant for submerged granular flows in a highly transparent manner. Both, the incompressible and compressible rheologies are implemented into OpenFOAM and various simulations at low and high Stokes numbers are conducted with both frameworks. We found a good agreement of the $\mu(J)$-$\phi(J)$-rheology with low Stokes number experiments, that incompressible models fail to describe. The combination of granular rheology, pore pressure, and drag model leads to complex phenomena such as apparent cohesion, remoulding, hydroplaning, and turbidity currents. The simulations give remarkable insights into these phenomena and increase our understanding of subaquatic mass transports

faSavageHutterFOAM 1.0: depth-integrated simulation of dense snow avalanches on natural terrain with OpenFOAM

Numerical models for dense snow avalanches have become central to hazard zone mapping and mitigation. Several commercial and free applications, which are used on a regular basis, implement such models. In this study we present a tool based on the open-source toolkit OpenFOAM® as an alternative to the established solutions. The proposed tool implements a depth-integrated shallow flow model in accordance with current practice. The solver combines advantages of the extensive OpenFOAM infrastructure with popular models from the avalanche community. OpenFOAM allows assembling custom physical models with built-in primitives and implements the numerical solution at a high level. OpenFOAM supports an extendable solver structure, making the tool well-suited for future developments and rapid prototyping. We introduce the basic solver, implementing an incompressible, single-phase model for natural terrain, including entrainment. The respective workflow, consisting of meshing, pre-processing, numerical solution and post-processing, is presented. We demonstrate data transfer from and to a geographic information system (GIS) to allow a simple application in practice. The tool chain is based entirely on open-source applications and libraries and can be easily customised and extended. Simulation results for a well-documented avalanche event are presented and compared to previous numerical studies and historical data.(VLID)2760104Version of recor

Aadh2p: an Arxula adeninivorans alcohol dehydrogenase involved in the first step of the 1-butanol degradation pathway

Additional file 3: Figures S3. Key compounds of the ß-oxidation - microarray studies. The SBGN style metabolic network depicts reversible (double headed arrow) and irreversible (single headed arrow) reactions catalyzed by the corresponding enzymes (rectangular square). Enzymes are enriched with color-coded fold change values of time resolved expression data of the respective genes. The colors represent upregulation (blue) and downregulation (red) of genes in cells shifted to medium containing 1-butanol as the carbon source compared to cells grown with glucose. Metabolites or enzymes occurring multiple times in the metabolic network are decorated with a clone marker (e.g. CoA) (produced using VANTED [2, 3])

Constraints on Entrainment and Deposition Models in Avalanche Simulations from High-Resolution Radar Data

Depth-integrated simulations of snow avalanches have become a central part of risk analysis and mitigation. However, the common practice of applying different model parameters to mimic different avalanches is unsatisfying. In here, we analyse this issue in terms of two differently sized avalanches from the full-scale avalanche test-site Vallée de la Sionne, Switzerland. We perform depth-integrated simulations with the toolkit OpenFOAM, simulating both events with the same set of model parameters. Simulation results are validated with high-resolution position data from the GEODAR radar. Rather than conducting extensive post-processing to match radar data to the output of the simulations, we generate synthetic flow signatures inside the flow model. The synthetic radar data can be directly compared with the GEODAR measurements. The comparison reveals weaknesses of the model, generally at the tail and specifically by overestimating the runout of the smaller event. Both issues are addressed by explicitly considering deposition processes in the depth-integrated model. The new deposition model significantly improves the simulation of the small avalanche, making it starve in the steep middle part of the slope. Furthermore, the deposition model enables more accurate simulations of deposition patterns and volumes and the simulation of avalanche series that are influenced by previous depositspublishedVersio

Multiphase Navier–Stokes Equations applied to landslide tsunamis : Numerical simulations of granular flows and their interaction with water bodies

publishedVersio

Numerical simulations of granular flows and their interaction with water bodies

Landslides can generate large tsunamis when falling into lakes and the sea. In order to protect coastal areas and communities we need to predict these events. Mathematical models have become a popular method for this task. However, current models neglect various aspects of either the landslide or the tsunami and predictions can be uncertain and unreliable. In my thesis I developed a model that considers the most important characteristics of landslides, tsunamis and their interaction. The model is tested with a large range of small scale laboratory experiments and with the simulation of a real event. The model gives us new and detailed insights into these catastrophic events. It improves our understanding and our capabilities to predict and mitigate future events