[aspect-devel] boundary pb

[Timo Heister]

Hey Cedric,

what is you boundary condition for the temperature on that boundary (and
does it also contain the perturbation term?)? (it should)

On Tue, Sep 16, 2014 at 11:09 AM, Cedric Thieulot <geogarfield at gmail.com>
wrote:

> Hi all,
>
> Anne, Menno and myself have been trying to run a model very similar to the
> convection-box.prm setup (based after the Blankenbach 1989 paper) albeit
> with a more
> complex rheology. Indeed, the setup involves a nonlinear visco-plastic
> rheology and it kept yielding all afternoon abnormal results in the right
> corner of the box.
> Visually abnormal, but also quantitatively abnormal when compared to the
> same setup ran with my ELEFANT code.
> In order to fix ideas, we decided to start all over again, and ran a few
> timesteps of the convection-box.prm setup … and witnessed the same
> abnormal behaviour for three versions of ASPECT (one from two weeks ago,
> i.e. the virtual box made for the GFZ workshop, one from a few weeks back,
> and one from last december).
> As you know, the convection-box is a buoyancy-driven experiment where the
> temperature field is initially prescribed to be
>  T(x,z)=(1-z)-0.01*cos(pi*x)*sin(pi*x)
> so that one expects the velocity field to be symmetric at t=0  (in
> magnitude, not direction). However attached are some screen captures of
> what we obtain.
> Please keep in mind that we get the convection-box.prm from git (or svn
> for the older version), that we do not modify it at all and that the file
> prescribes free slip on all sides.
> So why does the velocity field display a kink on the right boundary ?
> Also by changing the temperature field to T(x,z)=(1-z)*+*0.01*cos(pi*x)*sin(pi*x)
> , the kink is reversed, as if there was a velocity prescribed on the
> boundary no matter what…
> Do you have any idea where this could come from ? Can someone replicate
> this probem with their version by running 1 timestep of the convection-box
> experiment ?
>
> Kind regards,
>
> Cedric, Anne & Menno
>
>
>
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>



-- 
Timo Heister
http://www.math.clemson.edu/~heister/
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