UMR 5672

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Turbulent thermal convection of a nematic liquid crystal

Stephan Weiss (Max Planck Institute for Dynamics and Self-Organization, Goettingen)
When Mar 26, 2018
from 11:00 AM to 12:00 PM
Where Amphi Schrödinger
Attendees Stephan Weiss
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Nematic liquid crystals (NLC) are liquids consisting of elongated or discoidal molecules that align their preferred axis parallel to each other. As a result, these liquids have anisotropic physical properties, including the heat conductivity and the diamagnetic susceptibility. In my talk I will report on two major investigations, we have conducted with the NLC 4-cyano-4'-pentylbiphenyl (5CB) as the working fluid in a thermal convection experiment. In the first part I will talk about the convective heat transport of 5CB under the presence of an external magnetic field. We found that such a field causes an increase of the heat transport. We explain this phenomenon with an alignment of the fluid molecules parallel to the magnetic field, and a subsequent increase of the heat conductivity inside the thermal boundary layers. The second part of my talk deals with thermal convection at temperatures, where the NLC undergoes a phase transition from the nematic to the isotropic phase. Fluid properties change only little during this transition, and therefore it is similar to phase transitions occurring in the earths mantle. This investigation might thus contribute to a better understanding of the mantle dynamics and its heat transport properties.

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