[aspect-devel] Question regarding heat fluxes

[John Naliboff]

Hi Ian,

That's definitely odd. At first glance I don't see anything in the input file that would cause that kind of difference between the surface and basal heat flow.  You do have different velocity boundary conditions for the top and bottom boundaries, but that should not cause that much of a difference in the heat flow.

As Eric mentioned, the scaling of the heat flux from the output file would be different for the top and bottom boundaries.  That's the only think I can think of right now as well.

I'm also running some 2D shell models right now and I'll check out how the surface and basal heat fluxes compare.  I don't think they have reached steady yet, but it will be good to see if they exhibit the same behavior.  I'll send some figures over later this afternoon.

Cheers,
John




On Nov 15, 2012, at 11:38 AM, Eric Heien wrote:

> Are you normalizing based on the size of the boundary?  One thing that is not obvious and that we've had troubles with is that the printed flux is not per unit area, but over the whole boundary area.  Maybe this should be changed?
> 
> -Eric
> 
> On Nov 15, 2012, at 9:27 AM, Ian Rose wrote:
> 
>> Hi all,
>> 
>> I have been doing some tests with aspect involving heat fluxes out of the
>> top and bottom boundaries, and am getting some behavior I don't
>> understand.
>> 
>> When the convection reaches steady state, the heat fluxes out of the top
>> and bottom should be equal and opposite, otherwise, of course, it wouldn't
>> be steady.  However, if I look at a simple convection model in with 2d
>> shells, I find that the flux out the top is considerably lower than the
>> flux out of the bottom at steady state.  I am attaching a prm file and a
>> plot of heat fluxes as demonstration.  The qualitative change at ~10 Gyr is
>> due to a transition from organized to chaotic convection.  The basic heat
>> flux story is unchanged, though.
>> 
>> Looking at the code for heat flux statistics, nothing seems obviously
>> wrong.  I should note that doing the same test for a box geometry where the
>> top and bottom have the same area produces the expected results.
>> 
>> Am I missing something about how this should work?  Any insights as to what
>> is going on would be appreciated.
>> Best,
>> Ian
>> 
>> PS All calculations are done with r1353
>> <test_flux.prm><flux.ps>_______________________________________________
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