Earthquake dynamics - Understanding Their physics from modeling soft glassy materials
Developing a quantitative connection between the physics of complex soft-glassy materials below yield stress and the dynamics of stick-slip faulting events leading to earthquakes. A novel formulation based on the multicomponent Lattice Boltzmann method is used to investigate fundamental issues related to natural seismicity, to find the interaction between spatially and temporally separated faulting events, as well as to determining the response of faults to external perturbations (i.e. induced seismicity) mimicking natural gas extraction and activities in injection wells. This earthquake model will then be fine tuned using inversion of surface seismic recordings.
Lagrangian analysis of rotating Rayleigh-Bénard turbulence
Dynamics of particles in cylindrical rotating Rayleigh-Bénard convection (RRBC) is studied using DNS, not only to understand the physics of RRBC, but also to investigate whether particles with a feedback reaction on the flow can influence the dynamics within the cell.
Lagrangian statistics is used to characterise flow structures and heat transport and statistics obtained in the cell center and near the top- and bottom plates are compared to study the role of boundary layers in RRBC. The cylindrical set-up moreover allows us to compare results directly to particle-tracking experiments in RRBC.
On top of Lagrangian statistics also clustering dynamics of particles with different properties, such as thermal inertia and buoyancy, is investigated. By including both mechanical and thermal two-way coupling we can analyse the influence of particles on the flow and study whether we can trigger a transition to enhanced heat transport, which can be beneficial for industrial applications.
Photo-bioreactors: saving algae from turbulence!
Understanding turbulent flow of (dense) suspensions is one of the key factors needed in order to upscale and thus increase the productivity of algae photo-bioreactors. Many studies investigated the rheology of dense suspensions in laminar flows, as well as the dynamics of dilute suspensions in turbulence. We study dense suspension of finite size particles (algae) under turbulent flow conditions using a Lattice Boltzmann solver. Direct numerical simulations will be used to assess the level of hydrodynamics stresses on individual algae. The knowledge of the multi-scale statistics of turbulent fluctuations, down to the individual alga, is key to develop models necessary to up-scale photo-bioreactor, select algae strain, optimize algae productivity and reduce bioreactors energy consumption.
(defended 20 December 2013, at University of Twente co-supervised with Detlef Lohse)