[aspect-devel] Negative pressure

[Lev Karatun]

Hi Wolfgang,

thank you for the quick reply. The pressure normalization was actually set
to "no". I tried changing it to "surface", but it made made it so that the
pressure across the entire model domain except for the very lop layer
became negative =(

Best regards,
Lev Karatun.

2016-03-09 22:50 GMT-05:00 Wolfgang Bangerth <bangerth at tamu.edu>:

> On 03/09/2016 07:51 PM, Lev Karatun wrote:
>
>>
>> For the model with a fairly simple setup (2D box, influx from the sides
>> of the
>> model, outflux from the bottom, no free surface) I'm getting negative
>> pressure
>> values in the middle of the lithosphere. Could you please give me an idea
>> of
>> what could be the reason for it?
>>
>
> The Stokes equations only determine the pressure up to a constant. So at
> the end of each time step, we normalize it: we either make sure that its
> average value over the entire domain is zero, or its average value over the
> top surface is zero. It seems like you have chosen the first of these
> options. This may result in a negative pressure in the domain.
>
> Best
>  W.
>
> --
> ------------------------------------------------------------------------
> Wolfgang Bangerth               email:            bangerth at math.tamu.edu
>                                 www: http://www.math.tamu.edu/~bangerth/
>
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