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CATEGORIES:Isaac Newton Institute Seminar Series
SUMMARY:Random geometric graphs for modelling the pore sys
tem in fibre-based materials - Schmidt\, V (Ulm)
DTSTART;TZID=Europe/London:20100331T160000
DTEND;TZID=Europe/London:20100331T170000
UID:TALK23993AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/23993
DESCRIPTION:A stochastic network model is developed which desc
ribes the 3D morphology\nof the pore system in fib
re-based materials. Such materials are used e.g.\n
for the so-called gas diffusion layer (GDL) in pol
ymeric fuel cells. In \nthe pore space of GDL esse
ntial transport processes take place\, like the\nd
iffusion of oxygen and hydrogen\, respectively\, t
owards the electrochemically\nactive sites\,or the
drainage of produced water.\n\nRecently\, various
models for the solid phase of GDL\, in particular
for\nthe fibre system itself\, have been develope
d where the pore space is \nconsidered as compleme
ntary set. However\, this indirect description of
\npore space often leads to very complex geometric
structures\, i.e.\, it is \ndescribed by huge set
s of voxels\, which make numerical simulations of
\ntransport processes quite complicated and comput
er time consuming\, \nespecially for large domains
.\n\nIn the present talk\, a mathematical model fo
r random geometric graphs\nis developed\, represen
ting the pore space directly. It can be applied e.
g. \nto investigate transport processes in GDL on
a large scale. We first model\nthe vertex set of t
he graph by a stack of 2D point processes\, which
can\nphysically be interpreted as pore centres. Ea
ch pore centre is then marked \nby its pore size.
In the second step\, the edge set of the graph is
constructed\,\nwhere the vertices are connected us
ing tools from graph theory and MCMC simulation. \
n\nThe model parameters are statistically fitted t
o real 3D data gained by means \nof synchrotron to
mography. Finally\, the stochastic network model i
s validated by\nconsidering physical characteristi
cs of GDL like their tortuosity\, i.e.\, the\ndist
ribution of shortest path lengths through the mate
rial relative to its thickness.\n\nThe talk is bas
ed on joint research with W. Lehnert\, I. Manke an
d R. Thiedmann.\n
LOCATION:Seminar Room 2\, Newton Institute Gatehouse
CONTACT:Mustapha Amrani
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