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Title:
Immersed boundary method for multiscale transport simulation in complex domains.

Speaker: Bernard Geurts (Multiscale Modeling and Simulation, Dept. Applied Mathematics, UTwente)
Time: March 1, 2018, 10:00–11:00
Location: Differ, Alexander-zaal

The understanding and exploitation of convective and dissipative transport in complex domains is a field of growing interest. Applications that come to mind are future heat batteries in which an effective exchange of an external flow with a porous matrix is crucial, fractal stirrers allowing for a strong intensification of mixing processes or 3D-printed wick structures for optimal passive heat transfer in phase-change systems. In all these applications, the flow of a continuum in a spatially complex domain is at the heart of the problem. This brings together challenges in the field of modeling multiphase systems, possibly with phase change effects, as well as, solving the resulting differential equation models in highly complex domains.

In the presentation, I will concentrate on immersed-boundary-type methods with which domains with an intricate structure can be represented efficiently and which allow an accurate and flexible numerical solution of the governing equations. This approach will be discussed in some detail and subsequently illustrated for a number of important applications. First, we turn our attention to flow through cylinders with embedded fractal orifices. The increase in (laminar) mixing efficiency which this configuration allows will be quantified for a range of fractal shapes. An excursion to enhanced control over chemical processes in a turbulent flow will be included. Subsequently, flow through fibrous porous media and associated heat transfer, are presented in which the dynamics is fully resolved down to the pore-scale. The permeability of a sample porous plug will be computed and compared directly to physical experiments.

The CCER seminars are aimed at researchers interested in computational approaches to (energy) research. The seminar is small-scale, typically 15 participants, and interactive, offering lots of room for discussion. If you'd like to attend, just This email address is being protected from spambots. You need JavaScript enabled to view it..

Title:
Simulation of particle-laden turbulent flow.

Speaker: Hans Kuerten (Multiphase & Reactive Flows)
Time: Feb. 8, 2018, 10:00–11:00
Location: Differ

In many applications related to energy, particle or droplet transport in turbulent flow plays a role. Examples are combustion of fuel particles (biomass or metal) and diesel injection. In our group we study methods and models for accurate simulations of particle- and droplet-laden turbulent flow.

For particle-laden homogeneous isotropic turbulence it is usually assumed that particle collisions are not important if the particle volume fraction is less than 10-3. In inhomogeneous turbulent flow much higher particle volume fractions can occur locally due to turbophoresis and particle clustering. We investigated the effects of particle collisions for this flow and studied the particle collision rate in order to enable stochastic collision modeling.

For particles larger than the smallest scale of turbulence, point-particle methods are inaccurate due to the use of correlations for the drag force which only hold if particles are sufficiently small. A way to improve these correlations is by particle-resolved DNS. We used this method in turbulent flow in a channel with an array of particles to determine optimal values for the coefficients in a correlation for the drag force. The use of this optimal correlation in point-particle DNS results in better agreement with the results for the particle-resolved simulation.

The CCER seminars are aimed at researchers interested in computational approaches to (energy) research. The seminar is small-scale, typically 15 participants, and interactive, offering lots of room for discussion. If you'd like to attend, just This email address is being protected from spambots. You need JavaScript enabled to view it..

Title:
An atomistic understanding of the good and bad of the metal halide perovskites for solar energy.

Speaker: Shuxia Tao (CCER)
Time: Jan. 18, 2018, 10:00–11:00
Location: Differ

The rapid improvement of perovskite solar cells has made them the rising star of the photovoltaics world and of huge interest to the academic community. The efficiency of solar cells based on hybrid perovskites has rapidly increased from an initial promising value of 9% in 2012 to over 22% in 2016, making this the fastest-advancing solar technology to date. Since their materials and operational methods are still relatively new, there is great opportunity for further research into the basic physics and chemistry around perovskites. The object of my talk is to give a brief introduction of this exciting field and to zoom in to the atomistic understanding of the composition-structure-property relation of perovskite materials. I will discuss the progress, challenges and opportunities in this field using a combination of latest literature and examples of our own research.

The CCER seminars are aimed at researchers interested in computational approaches to (energy) research. The seminar is small-scale, typically 15 participants, and interactive, offering lots of room for discussion. If you'd like to attend, just This email address is being protected from spambots. You need JavaScript enabled to view it..

Multiscale Simulations of Polymer Membranes for Fuel and Flow Batteries
Soumyadipta Sengupta, Alexey V. Lyulin

Speakers: Soumyadipta Sengupta, Alexey V. Lyulin (CCER, TU/e Group Theory of Polymers and Soft Matter)
Time: Dec. 14, 2017, 10:00–11:00
Location: Differ

Redox flow batteries (RFBs) possess remarkable properties of independent power and energy scaling, long cycle life, fast response, and marginal self-discharge during storage. They have been recognized as perspective electrochemical grid storage devices. An ion-exchange polyelectrolyte membrane is a crucial battery component that isolates the electrolytes and prevents their cross-mixing, and allows transport of charge carriers to complete the electrochemical circuit. A suitable membrane should be stable against oxidation and reduction by the electrolyte components (for example, in the case of all-vanadium RFB, by VO2+ and V2+ cations), display high charge carriers permeability (protons in the case of all-vanadium RFB) and conductivity, and suppressed electrolyte permeability for longer cycle life. In this presentation I will give an overview of our recent fully-atomistic molecular-dynamics simulations of some perspective membranes for RFBs and high-power-density low-temperature polyelectrolyte-membrane fuel cells (PEMFC). I will discuss our results on structure and vehicular proton transport in Nafion, PFIA and some other membranes based on the perspective nanocomposites with graphene oxide as a filler. Our approach for upscaling the atomistic simulations will be presented as well.

The CCER seminars are aimed at researchers interested in computational approaches to (energy) research. The seminar is small-scale, typically 15 participants, and interactive, offering lots of room for discussion. If you'd like to attend, just This email address is being protected from spambots. You need JavaScript enabled to view it..