[petsc-users] A question about ghost cells

[leejearl]

Hi, Matt:
     Thank your for your reply, and it is what I needed.

leejearl


On 2016年10月28日 21:08, Matthew Knepley wrote:
> On Fri, Oct 28, 2016 at 8:05 AM, leejearl <leejearl at 126.com 
> <mailto:leejearl at 126.com>> wrote:
>
>     Hi, Matt:
>         Thank you for your help. It is the answer which I expect.
>         But， I have an another equestion. Can I obtain the coordinates
>     of the ghost cells:
>
>
> I am not sure I understand. By default, Plex stores coordinates only 
> for vertices. Also, ghost cells
> do not have a full complement of vertices because they are only used 
> to define a state on the other
> side of a face. Does that make sense?
>
>   Matt
>
>         Thanks,
>
>     leejearl
>
>     On 2016年10月28日 19:56, Matthew Knepley wrote:
>>     On Fri, Oct 28, 2016 at 6:32 AM, leejearl <leejearl at 126.com
>>     <mailto:leejearl at 126.com>> wrote:
>>
>>         Hi, everyone:
>>
>>             I have a distributed DMPlex representing a 2D finite
>>         volume mesh. I distributed it using the function
>>         "DMPlexDistribute()".
>>
>>         Then, I constructed the ghost cells using
>>         "DMPlexConstructGhostCells()".
>>
>>            The question is that I want to determine which cell is
>>         ghosted. I obtained all the cells using
>>         "DMPlexGetHeightStratum()", and
>>
>>         how can I kown which cell is ghosted?
>>
>>
>>     1) The ghost cells are marked as "hybrid", so you can call
>>
>>       ierr  = DMPlexGetHybridBounds(dm, &cEndInterior, NULL, NULL,
>>     NULL);CHKERRQ(ierr);
>>       ierr  = DMPlexGetHeightStratum(dm, 0, NULL, &cEnd);CHKERRQ(ierr);
>>
>>     and then the ghost cells are [cEndInterior, cEnd).
>>
>>     2) There is also a label "ghost" which marks the ghost faces, and
>>     ghost cells which are non-local
>>
>>       Thanks,
>>
>>         Matt
>>
>>            Thanks, all the helps are appreciated.
>>
>>
>>         leejearl
>>
>>
>>
>>
>>
>>
>>     -- 
>>     What most experimenters take for granted before they begin their
>>     experiments is infinitely more interesting than any results to
>>     which their experiments lead.
>>     -- Norbert Wiener
>
>
>
>
> -- 
> What most experimenters take for granted before they begin their 
> experiments is infinitely more interesting than any results to which 
> their experiments lead.
> -- Norbert Wiener

-- 
李季
西北工业大学航空学院流体力学系
Phone: 17792092487
QQ: 188524324

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