[aspect-devel] boundary velocity function expressions
John Naliboff
jbnaliboff at ucdavis.edu
Mon Oct 10 23:14:05 PDT 2016
Hi Anne,
Thanks for pointing that out!
Payman - from the file two_merged_boxes.cc documentation section:
"An example application of this geometry is to prescribe a velocity on "
"the lithospheric plates, but use open boundary conditions underneath. "
Seems like this is exactly what you are looking for.
Cheers,
John
*************************************************
John Naliboff
Assistant Project Scientist, CIG
Earth & Planetary Sciences Dept., UC Davis
> On Oct 10, 2016, at 10:37 PM, Glerum, A.C. (Anne) <A.C.Glerum at uu.nl> wrote:
>
> Hi Payman and John,
>
> It's possible to prescribe two different velocity boundary conditions on the vertical boundaries of a box domain when you use the geometry model "two merged boxes". For example, a prescribed inflow of the lithosphere and free slip in the mantle.
>
> Cheers,
> Anne
>
>
> On 11 Oct 2016, at 06:55, John Naliboff <jbnaliboff at ucdavis.edu <mailto:jbnaliboff at ucdavis.edu>> wrote:
>
>> Hi Payman,
>>
>> Glad the input file helped.
>>
>>> However, how can I prescribe velocity to a segment of a boundary and let the rest of that boundary be tangential?
>>
>> In effect, you would like part of a vertical wall (right boundary) to be free-slip, while the other part has the vertical velocity prescribed? Hmm, I’m not sure ASPECT is setup to do a ‘mixed’ velocity boundary. In fact, I’m having a hard time thinking of a study that does this.
>>
>> In the case you describe below, do you need to prescribed both the vertical velocity and not just the horizontal velocity?
>>
>> Cheers,
>> John
>>
>> *************************************************
>> John Naliboff
>> Assistant Project Scientist, CIG
>> Earth & Planetary Sciences Dept., UC Davis
>>
>>
>>
>>
>>
>>
>>> On Oct 10, 2016, at 7:22 PM, Payman Janbakhsh <payman.janbakhsh at mail.utoronto.ca <mailto:payman.janbakhsh at mail.utoronto.ca>> wrote:
>>>
>>> Thank you John,
>>> Actually the continental extension prm file that you sent to Mohamed helped me to figure out the velocity prescription to different boundaries using functions.
>>>
>>> However, how can I prescribe velocity to a segment of a boundary and let the rest of that boundary be tangential?
>>> For instance, considering a right boundary, a mantle lithospheric slab having its own westward prescribed velocity, but the rest of that boundary (mantle) be tangential.
>>>
>>> Thanks again
>>>
>>> Payman
>>>
>>> From: Aspect-devel [mailto:aspect-devel-bounces at geodynamics.org <mailto:aspect-devel-bounces at geodynamics.org>] On Behalf Of John Naliboff
>>> Sent: October 10, 2016 12:25 PM
>>> To: aspect-devel at geodynamics.org <mailto:aspect-devel at geodynamics.org>
>>> Subject: Re: [aspect-devel] boundary velocity function expressions
>>>
>>> Hi Payman,
>>>
>>> Specifying the velocity on the boundaries works a bit differently than what you have outlined below.
>>>
>>> In 2D you need to specify velocity components for x and y, which you do via the function. You can control how the velocity on different boundaries (ex: left & right) by including conditional statements in your functions based on the position (defined by 'x' and 'y' in 2D).
>>>
>>> You can also specify that only certain components of the function apply to a certain boundary (i.e. only x velocity from functions is applied to left/right boundary).
>>>
>>> If there is a specific setup you are thinking of, can you sent over a basic parameter file that we can look over?
>>>
>>> Cheers,
>>> John
>>>
>>> *************************************************
>>> John Naliboff
>>> Assistant Project Scientist, CIG
>>> Earth & Planetary Sciences Dept., UC Davis
>>> On 10/09/2016 03:08 PM, Payman Janbakhsh wrote:
>>> Hi,
>>> I’m trying to implement the following for a 2D problem:
>>>
>>> Set Prescribed velocity boundary indicators = left : function , right : function
>>>
>>> But get error when trying to give Function expressions in: set Function expression =
>>> I have tried separating 2 velocity components with semicolon and separate function expressions with comma .
>>> Example:
>>> Left boundary function right boundary function
>>> Set Function expression = if(z>=1000 , 1, 0) ; 0 , if(z>=1000, -1,0) ; 0
>>>
>>> I’ve tried many ways including below but all give errors or nonsensical velocity Glyphs:
>>> Set Function expression = left: if(z>=1000 , 1, 0) ; 0 , right: if(z>=1000, -1,0) ; 0
>>> Set Function expression = left = if(z>=1000 , 1, 0) ; 0 , right= if(z>=1000, -1,0) ; 0
>>> Set Function expression = ( if(z>=1000 , 1, 0) ; 0 ) , ( if(z>=1000, -1,0) ; 0 )
>>> …
>>>
>>> How can I separate multiple function expressions each for its corresponding boundary indicator ?
>>>
>>> Thanks
>>>
>>> Payman
>>>
>>>
>>>
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