[time-nuts] Thunderbolt stability and ambient temperature

Bruce Griffiths bruce.griffiths at xtra.co.nz
Fri Jun 12 01:54:11 UTC 2009


John

That doesn't appear to reproduce what was claimed to have been observed
at all.
The input is more like a step function that switches from hot to cold.
This allows the simulated bar to reach a steady state temperature
distribution before decaying smoothly to a lower temperature.

Bruce

J. Forster wrote:
> The effect that was described was absolutely NOT a result of thermal
> conductivity being a function of temperature.
>
> It was a dynamic effect... a transient condition. The result of applying a
> short heat pulse to a long Time Constant, distributed system.
>
> Do the simulation I suggested hours ago.
>
> -John
>
> ==============
>
>
>   
>>> Tom
>>>
>>> The thermal conductivity isnt constant with temperature.
>>> It also varies between different crystalline forms of the same material.
>>> This can be seen in more comprehensive tables of thermal conductivity.
>>> In particular at cryogenic temperatures the thermal conductivity can
>>> change dramatically (eg in superconductors)
>>>
>>> Bruce
>>>       
>> Excellent. Not constant; and perhaps not even linear?
>>
>> If you run across a thermal conductivity table for steel
>> from say 0 to 1000 C let us know. From that graph we
>> should be able to calculate what Rex felt when he put the
>> red hot (1500 F?) end of the 1 inch bar into cold water.
>>
>> Better yet, if some metal or material has an even more
>> pronounced thermal conductivity function it would make
>> a great party trick.
>>
>> /tvb
>>
>>
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>>     
>
>
>
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