Awards

Dr. Max Hodapp is one of two winners of the SWICCOMAS prize 2019 and has been selected as the Swiss-based candidate for the 2018 ECCOMAS PhD thesis award on Computational Methods in Applied Sciences and Engineering.

For the thesis dissertation:

“On flexible Green function methods for atomistic/continuum coupling”
Thesis director – William Curtin, EPFL

Abstract:
Atomistic/continuum (A/C) coupling schemes have been developed during the past twenty years to overcome the vast computational cost of fully atomistic models, but have not yet reached full maturity to address many open problems in metal plasticity. This thesis has therefore been devoted to the development of an extension of the coupled atomistic/discrete dislocations method to three dimensions (CADD-3d). To simulate the motion of hybrid dislocations along A/C interfaces a simplified solution procedure, which updates the boundary conditions on the atomistic problem based on the Green function of the entire dislocation network, has been introduced and validated. In order to solve the complementary elasticity problem a discrete boundary element method (DBEM) has been developed and implemented using an efficient hierarchical representation of the dense system matrices. The coupled atomistic/DBEM problem is solved using a fast stabilized monolithic Newton-Krylov method and an improvement of the overall accuracy by several orders of magnitude has been found in comparison with naive clamped boundary conditions. In addition, a semi-monolithic solution procedure has been conceptually proposed for CADD-3d which iterates between the entire physical and the discrete dislocation problem. Using the atomistic/DBEM coupling the computational complexity of this method becomes highly favorable in comparison with existing schemes in terms of the required degrees of freedom if many dislocations have passed the A/C interface.

 

Dr. Paola Bacigaluppi is one of two winners of the SWICCOMAS prize 2019

For the thesis dissertation:

“High Order Fully Explicit Residual Distribution Approximation for Conservative and Non-Conservative Systems in Fluid Dynamics”
Thesis director – Rémi Abgrall, UZH

Abstract:
In this work we collect several studies that embroil diverse techniques to tackle some of the many unsolved challenges linked to the study of strong interacting discontinuities for multidimensional, time-dependent hyperbolic systems of equations in Fluid Dynamics written both in conservative and non-conservative form.

To this end, we propose methodologies based on Residual Distribution schemes, which can be reinterpreted as non-standard Finite Volume and Finite Element approaches (Abgrall, Computational Methods in Applied Mathematics 2018).  In particular, we develop fully explicit high-order oscillation-free numerical methods without exceeding dissipation across shocking waves and allow to work directly with non-conservative variables, like pressures and internal energies, without any loss of conservation, and thus of information.

The robustness and accuracy of the novel strategies are assessed on several challenging benchmark problems in the context of the Euler equations for single phase flows and reduced Baer and Nunziato type systems for two-phase flows.


Dr. Joseph B. Nagel won The SWICCOMAS prize 2018

For the thesis dissertation:

“Bayesian techniques for inverse uncertainty quantification”

ETH Zürich – Thesis director Prof. Dr. Bruno Sudret

Abstract:

The thesis deals with Bayesian techniques for inverse problems under uncertainty. A probabilistic framework for treating both epistemic (lack of knowledge) and aleatoric uncertainties (natural variability) is established. Hamiltonian Monte Carlo is then proposed in order to tackle the computational challenge of exploring possibly high-dimensional posterior distributions. Beyond that, novel approaches to computational Bayesian inference are developed on the basis of variational methods and polynomial chaos expansions. They try to overcome the shortcomings of traditional sampling-based Markov chain Monte Carlo algorithms. A variety of problems, either simple or realistically complex, from the domain of civil, mechanical and hydrological engineering serve for demonstration purposes.