« Fluid phase change simulation in porous and cracked media based on multimodal full-field measurements»

Project summary

The performance of reinforced concrete containment structures is analysed with respect to their ability to prevent a fluid from percolating through the wall barier. For concrete structures, the leaks break down into two flows, one of which passes through the porous networks of the cement matrix and the other passes through eventual cracks and crack network space. Conventionally, the fluids used to experimentally test the tightness are either liquid water or a neutral gas. In reality, the percolating fluid could be more complex, consisting of a multiphase mixture of air and hot water vapour.

The present project aims to pursue towards the quantitative experimental analysis and numerical multi-physics modelling of the two-phase (hot steam and air) flow and condensation processes during injection into fractured concrete material. Indeed, first ever experiments of in-situ quantitative visualization of vapour condensation in cracked concrete through high-speed neutron radiography have been performed revealing a complex interplay between pressure and sorption flow phenomena and a significantly different behaviour between dry and saturated sample.

Project summary

The project aims at studying numerically the rheological properties of suspensions of hard to soft spheres, dispersed in a Newtonian fluid, which are found in many industrial and geophysical processes. Using a DEM approach, and a recently developed model of lubricated contact, we will study the role of particle deformability, an essential ingredient which is usually overlooked in existing simulations. Deformability is crucial to regularize the divergence of the lubrication forces at contact, but its effects on the suspension rheology remain to be investigated in depth.

Our recently developed model of lubricated contacts [Chevremont et al., Powder Tech. 2020] produced new results related to the role of contact friction [Chevremont et al., Phys. Rev. Fluids 2019] and led to a complete set of constitutive relations for dense suspensions [Chevremont et al., arxiv.org/abs/2103.03718]. This model is implemented in the open source code yade-dem.org. We are now able to tackle efficiently the case of slightly deformable particles, for which lubrication, friction and deformability are strongly coupled.

At a macroscopic level, these effects are ignored by the established “μ(Iv)” constitutive model of hard sphere suspensions, as there is a new dimensionless number characterizing the ratio of viscous stresses to particle stiffness, the capillary number Ca. One goal of this project is to extend the μ(Iv) rheology to a phenomenological μ(Iv,Ca) rheology, which we will characterize by DEM simulations with systematic variations of the particle deformability, in a large range of volume fractions and shear rates.

We will also focus on viscous resuspension, which occurs when an external force field (typically gravity) is exerted on a flowing buoyant suspension, leading to gradients of volume fraction. This phenomenon is closely related to particle migration and the study of the transient regime from a homogeneous (non flowing) suspension to the re-suspended steady state will lead to improve existing continuum models by determining expansional viscosity.

This numerical project will be conducted in close relation to an ongoing experimental study.

The University of Bath is inviting applications for the following PhD project commencing in October 2021:

“Untangling the mechanical behaviour of grass-rooted soil layers for sustainable infrastructure construction”

For more detailed information, please see https://www.findaphd.com/phds/project/untangling-the-mechanical-behaviour-of-grass-rooted-soil-layers-for-sustainable-infrastructure-construction/?p130622

About the position: We have a vacancy for a 3-year R&D project within computational geomechanics at BAW Bundesanstalt für Wasserbau Federal Waterways Engineering and Research Institute Department of Geotechnical Engineering in Karlsruhe, Germany. The R&D-position’s main objective is to improve open source geomechanical analysis tools and to qualify the candidate for research positions.

Duties of the position: The R&D project aims at the validation and further development of poroMechanicalFoam, an openFOAM based FVM-model for hydro-mechanical analysis of flow-structure-soil interactions considering variable soil saturation. Based on analytical solutions and experimental data the impact of spatial and temporal discretization on robustness and accuracy shall be determined. The model performance shall be tested based on case studies from the geotechnical engineering practice at BAW considering representative aspects among others anisotropy of the mechanic and/or hydraulic properties, advanced soil material models (bounding surface plasticity), variable saturation and gas entrapment below the phreatic surface. In the final stage predictable failure mechanisms are to be addressed within the framework of the second order work concept. If desired, there is possibility for laboratory tests for characterization of soil properties and or/ identification of aspects yet not properly captured in poroMechanicalFoam.

The Institute of Geotechnical Engineering at the University of Stuttgart (IGS) invites applications from motivated, committed and talented candidates for the position of a

Research / Teaching Assistant (PhD Student)

in the field of Computational Geotechnics, especially for modelling large deformations and its application in the field of Geotechnical Engineering.

More information in this attached file.

I would like to draw your attention to the post of Research Assistant/Research Associate, in the School of Engineering at Newcastle University in the area of computational geotechnics. The successful applicant will join the ACHILLES Programme at Newcastle University to carry out high-quality research on infrastructure embankments and the impacts of climate change.

https://jobs.ncl.ac.uk/job/Newcastle-Research-AssistantAssociate-in-Computational-Geotechnics/670190501/

The application is open until the 18th May 2021.

The Institute of Geotechnical Engineering of the University of Natural Resources and Life Sciences, Vienna is currently looking for 2 PhD candidates for the research project STRECROPA.Please see attached the description of the research project and of the two PhD positions:

• Experimental modelling of construction of cross passages of shallow tunnels
• Numerical modelling of construction of cross passages of shallow tunnels

We have a vacancy for a 3-year PhD fellowship at the Department of Geoscience and Petroleum (IGP). The position is within computational energy geomechanics. The research will include development and implementation of models for finite element method (FEM) analysis with poro-elasto-plasticity. The PhD student will be assigned to the Department of Geoscience and Petroleum (IGP) and will be supervised by Prof. Rune Holt and co-supervised by Dr. Euripides Papamichos from SINTEF Industry.

More info: PhD position in Numerical Analysis in Energy Geomechanics – IV-142/21 (205621) | NTNU – Norwegian University of Science and Technology (jobbnorge.no)

Application Deadline 07 June 2021.