# Jerusalem Mathematics Colloquium

Thursday, 14th April 2005, 4:00 pm

Mathematics Building, Lecture Hall 2

##

Raz Kupferman

(Hebrew University)

"The high Weissenberg number problem"

** Abstract: **

Most fluids we are accustomed to are Newtonian: their
internal state of stress only depends on their instantaneous
local distortion (in other words they have no memory). Water
and air are examples of Newtonian fluids. Complex fluids,
such as corn syrup, blood, and molten plastics have memory:
their state of stress is a function of their entire
deformation history. Computational rheology is concerned
with the development of numerical methods for predicting
flows of such fluids.

Since the early 1970's this field has
been haunted by the so-called high Weissenberg number
problem---the breakdown of ALL computational methods at
parameter regimes in which memory is manifest. Recent work
sheds light on the origin of this breakdown, which has
remained of a mystery for over 3 decades. In fact, this
breakdown can be remedied by a simple change of variables.

Joint work with Raanan Fattal

Light refreshments will be served in the faculty lounge at 3:30.

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