[CIG-SHORT] open_free_surface

[Brad Aagaard]

Birendra,

The open_free_surface parameter controls whether the traction 
perturbation is applied when the fault opens. For a surface with sliding 
friction, we would expect zero tractions (a free surface) when the fault 
opens, so that any initial tractions should not be applied. However, 
when simulating something like a dike where the initial tractions 
represent fluid pressures that cause fault opening, then we want the 
initial tractions to continue to be applied when the fault opens.

The default value is true, because in most cases we are simulating 
sliding friction.

Regards,
Brad


On 11/19/2012 02:05 PM, Birendra jha wrote:
> Dear developers,
>
> I am slightly confused by the open_free_surface parameter. I thought this is supposed to allow fault-opening even if the normal traction on the fault is non-zero. But in FaultCohesiveDyn.cc we have:
>
>   if (slipNormal < _zeroTolerance || !_openFreeSurf) {
>        // if no opening or flag indicates to still impose initial
>        // tractions when fault is open.
>
> Should it be "_openFreeSurf" instead of "!_openFreeSurf"?
> Also, the default value for this parameter is "true" (in the constructor), correct?
>
> Thanks
> Birendra
>
>
> --- On Mon, 11/19/12, Brad Aagaard <baagaard at usgs.gov> wrote:
>
>> From: Brad Aagaard <baagaard at usgs.gov>
>> Subject: Re: [CIG-SHORT] VTK Stress Output
>> To: cig-short at geodynamics.org
>> Date: Monday, November 19, 2012, 9:56 PM
>> Bobby,
>>
>> I verified that there is no difference in VTK output for the
>> stresses in
>> 2-D between v1.7 and v1.8. We do list the stress tensor as a
>> vector in
>> the VTK file because we provide three components; ParaView
>> interprets
>> the components as x (stress_xx), y (stress_yy), and z
>> (stress_xy).
>>
>> When using HDF5/Xdmf output we explicitly split the
>> components into
>> stress_xx, stress_yy, and stress_xy in the Xdmf file. In the
>> HDF5 file
>> we have the three components in the same dataset.
>>
>> Regards,
>> Brad
>>
>> On 11/19/12 7:31 AM, BOK10 at pitt.edu
>> wrote:
>>> Hi,
>>>
>>> I'm running a simulation and looking for the VTK stress
>> output. Before I
>>> updated I would get Stress_xx, Stress_yy, and
>> Stress_xy. But now I only
>>> get stress_x, stress_y, and stress_z. How can I get the
>> output to have xx,
>>> yy, and xy?
>>>
>>> Bobby
>>>
>>> _______________________________________________
>>> CIG-SHORT mailing list
>>> CIG-SHORT at geodynamics.org
>>> http://geodynamics.org/cgi-bin/mailman/listinfo/cig-short
>>>
>>
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>