[aspect-devel] Handing nodes problem

[John Naliboff]

Hi Phil,

300 km is definitely on the high side and in the past with other codes 
I've used down to 50 km without any odd behavior (spurious velocities, 
etc) appearing. Of course the absolute velocity magnitudes, element 
type, etc, etc, play a role.

If you see "odd behavior" in some cases please do pass that info onto 
this list-serv! The failures are just as helpful as the successes and 
all that jazz ;)

Cheers,
John

*************************************************
John Naliboff
Assistant Project Scientist, CIG
Earth & Planetary Sciences Dept., UC Davis

On 05/22/2017 09:31 AM, HERON, PHILIP J. wrote:
> Hi John,
>
> Thanks for the message. I hadn't tried such an extreme gradation of 
> 300km - I think I stopped at about 100 km - but I will give that a go. 
> Thanks for the advice.
>
> Cheers,
>
> Phil
>
>
> ------------------------------------------------------------------------
> *From:* Aspect-devel [aspect-devel-bounces at geodynamics.org] on behalf 
> of John Naliboff [jbnaliboff at ucdavis.edu]
> *Sent:* May 22, 2017 5:21 PM
> *To:* aspect-devel at geodynamics.org
> *Subject:* Re: [aspect-devel] Handing nodes problem
>
> Hi Philip,
>
> I've applied this type of velocity boundary condition to a continental 
> extension problem. In a 500 km deep model I had uniform outflow in the 
> top 100 km (lithosphere), a gradation from outflow to inflow between 
> 100-400 km depth and constant inflow in the bottom 100 km.This was all 
> done through functions in the parameter file.
>
> The trick typically is to make sure the gradation between in 
> inflow/outflow is not too sharp, hence why I did it over a few hundred 
> km. You probably also need to be careful with any variations in grid 
> resolution.
>
> I believe a few other people have tried something similar with other 
> models.
>
> Let me know if it would be helpful to see the exact function 
> implementation I used.
>
> Cheers,
> John
>
> *************************************************
> John Naliboff
> Assistant Project Scientist, CIG
> Earth & Planetary Sciences Dept., UC Davis
> On 05/22/2017 12:15 AM, HERON, PHILIP J. wrote:
>> Going back to Cedric's point, are there any recommendations for applying multidirectional velocities to a boundary? For example, applying a convergent velocity to the lithosphere and a outflow to the asthenosphere (in horizontal 2D models)? I can't see any examples in the cookbooks where such velocities have been applied - has it been done?
>>
>> I started looking into this a while ago - will have a look where I got to. From what I remember, it was very difficult to transition between horizontal directions and sounds similar to Lev's issues.
>>
>>
>> ________________________________________
>> From: Aspect-devel [aspect-devel-bounces at geodynamics.org] on behalf of cedric thieulot [c.thieulot at uu.nl]
>> Sent: May 19, 2017 6:17 PM
>> To:aspect-devel at geodynamics.org
>> Subject: Re: [aspect-devel] Handing nodes problem
>>
>> Looking at the viscosity field, it kinda looks like suspicious in the darkest red regions, and reminds me of
>> simulations whose velocity field is not smooth and converged, thereby leading to anormal element-based strainrate patterns.
>> Ce/
>>
>>
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>
>
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