[CIG-SHORT] CIG-SHORT Digest, Vol 98, Issue 27
Charles Williams
willic3 at gmail.com
Tue Nov 25 13:25:31 PST 2014
Hi Jeanne,
It sounds to me like there are 3 ways you could go:
1. Just use the nodeset corresponding to the entire ground surface and provide enough points to do a linear interpolation. This would mean you need a set of points (with zero tractions) just outside the inner domain, and another set around the edge of the ground surface.
2. Define an inner domain for Cubit/Trelis:
group “loadground” add node in face_zpos
group “loadground” remove node with x_coord > 30001
group “loadground” remove node with x_coord < -30001
etc.
nodeset 17 group loadground
nodeset 17 name “loadground”
Then you just provide enough points to do a linear interpolation within loadground (or just give values at each node if there aren’t that many).
3. Write a simple Python (or other language) script to read the coordinates of the points in your nodeset, either from the input mesh, or from a VTK or HDF5 file that includes the nodeset. You can then apply any function you want based on the nodeset coordinates, and write a spatial database from that.
Let me know if one of these methods seems best to you.
Cheers,
Charles
> On 26/11/2014, at 9:07 am, Sauber-Rosenber, Jeanne M. (GSFC-6980) <jeanne.m.sauber-rosenberg at nasa.gov> wrote:
>
> Matt,
> Thanks; I am awaiting the specific CUBIT commands to create the subdomain on the z+face.
> The Pylith part I believe I know how to do.
> Thanks,
> Jeanne
> ________________________________________
> From: cig-short-bounces at geodynamics.org [cig-short-bounces at geodynamics.org] on behalf of cig-short-request at geodynamics.org [cig-short-request at geodynamics.org]
> Sent: Tuesday, November 25, 2014 3:00 PM
> To: cig-short at geodynamics.org
> Subject: CIG-SHORT Digest, Vol 98, Issue 27
>
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> 1. Re: CIG-SHORT Digest, Vol 98, Issue 25 (Matthew Knepley)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 25 Nov 2014 11:33:58 -0600
> From: Matthew Knepley <knepley at mcs.anl.gov>
> To: "cig-short at geodynamics.org" <cig-short at geodynamics.org>
> Cc: "C.Williams at gns.cri.nz" <C.Williams at gns.cri.nz>
> Subject: Re: [CIG-SHORT] CIG-SHORT Digest, Vol 98, Issue 25
> Message-ID:
> <CAMYG4GkSdnJu3NOQmPTNWC60R-pdhFqyOHb6YPE5sOnPuT4bsQ at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> On Tue, Nov 25, 2014 at 7:33 AM, Sauber-Rosenber, Jeanne M. (GSFC-6980) <
> jeanne.m.sauber-rosenberg at nasa.gov> wrote:
>
>> Subject: CIG-SHORT Digest, Vol 98, Issue 25
>>
>> Brad and Charles,
>>
>> Attached is a figure describing the basic problem (but it does
>> not correspond exactly to the attached
>> journal files). Yes, I just want a surface load that spatially varies in
>> the immediate region surrounding a (GPS) site.
>> Attached are my geometry and meshing files with my poor attempt at
>> creating a subdomain commented out. Last
>> time, months ago, I submitted attachments and they didn't come through so
>> I cc'd your individual accounts as well.
>>
>
> I think Charles is correct here. The idea is to provide a spatial database
> that mimics this layout. I think you need to
> provide the load at each point in the square, and 0 for the square
> boundary. I don't think the interpolation method will
> matter very much.
>
> After that works for the static problem, you can provide a set of slices
> like this for the time history.
>
> Thanks,
>
> Matt
>
>
>> THANKS,
>> Jeanne
>>
>>
>> Hi Jeane,
>>
>> I?m a little unclear on your question. Am I correct that what you want to
>> do is have a variable surface load with different time histories throughout
>> the nodeset? Or do you just want a variable surface load that only varies
>> spatially? If that?s the case, you just need a single nodeset, and you
>> don?t need to provide a load at every location. You just need enough
>> points to allow linear interpolation (2D variation). The key is to make
>> sure you provide values that either coincide with or go outside the domain
>> of the surface.
>>
>> If you want a subdomain, I think the easiest thing is to create a group,
>> because you can perform logical operations on them. You can then do things
>> like:
>>
>> group ?test_group? remove node with x_coord > 10001
>>
>> Once you?ve defined the group the way you want you can then create a
>> nodeset from it.
>>
>> Sorry if I haven?t really answered your question, but I think I need some
>> more details on what you?re trying to do.
>>
>> Cheers,
>> Charles
>>
>>
>>
>>> On 24/11/2014, at 7:05 am, Sauber-Rosenber, Jeanne M. (GSFC-6980) <
>> jeanne.m.sauber-rosenberg at nasa.gov> wrote:
>>>
>>> A number of us spoke briefly with Brad at the Stanford workshop about
>> expanding (3D/hex)
>>> step18 & step 19 (one surface load at 0,0) to input multiple loads. IF
>> I would like
>>> to input a variable surface load over a portion of the positive Z face,
>> I believe Brad
>>> suggested creating a separate subdomain/nodeset on the +z face (?) In
>> CUBIT, do I create
>>> first the +z node set (CUBIT commands in step 1 below) and then I create
>> a subset by removing nodes
>>> outside a center region (incomplete CUBIT command in step 2 below)?
>>>
>>> If I should create a subset of the z+ surface to input surface loads
>> commands:
>>> 1. Do I need to input a load at every point in the subdomain to be
>>> able to use linear interpolation?
>>> 2. Do you put the 0 tractions on the edges of this subdomain or on the
>>> edges of +z-face, i.e. such as in the step 19 example given in the
>> spatialdb/tractions_axial_pressure.spatialdb file?
>>>
>>> I tried but never succeeded in creating a subdomain in CUBIT.
>>>
>>> Step 1:
>>> # ----------------------------------------------------------------------
>>> # Create node set for +z face
>>> # ----------------------------------------------------------------------
>>> group "face_zpos" add node in surface 1
>>> nodeset 16 group face_zpos
>>> nodeset 16 name "face_zpos"
>>>
>>> Step 2:
>>> #-----------------------------------------------------------------------
>>> #create nodeset for load/unload set
>>> #-----------------------------------------------------------------------
>>> what OTHER commands?
>>> nodeset 17 in surface all with x_coord > 10001 remove
>>> nodeset 17 in surface all with x_coord < -10001 remove
>>> nodeset 17 in surface all with y_coord > 10001 remove
>>> nodeset 17 in surface all with y_coord < -10001 remove
>>>
>>> Thanks,
>>> Jeanne Sauber
>>> _______________________________________________
>>> CIG-SHORT mailing list
>>> CIG-SHORT at geodynamics.org
>>> http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-short
>>
>> Charles A. Williams
>> Scientist
>> GNS Science
>> 1 Fairway Drive, Avalon
>> PO Box 30368
>> Lower Hutt 5040
>> New Zealand
>> ph (office): 0064-4570-4566
>> fax (office): 0064-4570-4600
>> C.Williams at gns.cri.nz
>>
>>
>>
>> ------------------------------
>>
>> Message: 2
>> Date: Mon, 24 Nov 2014 08:56:03 -0800
>> From: Brad Aagaard <baagaard at usgs.gov>
>> To: <cig-short at geodynamics.org>
>> Subject: Re: [CIG-SHORT] multiple loads in step 18 & step 19
>> Message-ID: <54736323.6060609 at usgs.gov>
>> Content-Type: text/plain; charset="utf-8"; format=flowed
>>
>> Jeanne,
>>
>> Can you send a simple cartoon/diagram with a physical description of
>> what you want to do to help us remember what you are trying to do? In
>> the diagram, focus on describing the physics not the PyLith parameters.
>> Once Charles and I understand the physics, we can help you translate it
>> into nodesets in CUBIT/Trelis and PyLith settings.
>>
>> Regards,
>> Brad
>>
>>
>> On 11/23/2014 04:54 PM, Charles Williams wrote:
>>> Hi Jeane,
>>>
>>> I?m a little unclear on your question. Am I correct that what you
>>> want to do is have a variable surface load with different time
>>> histories throughout the nodeset? Or do you just want a variable
>>> surface load that only varies spatially? If that?s the case, you
>>> just need a single nodeset, and you don?t need to provide a load at
>>> every location. You just need enough points to allow linear
>>> interpolation (2D variation). The key is to make sure you provide
>>> values that either coincide with or go outside the domain of the
>>> surface.
>>>
>>> If you want a subdomain, I think the easiest thing is to create a
>>> group, because you can perform logical operations on them. You can
>>> then do things like:
>>>
>>> group ?test_group? remove node with x_coord > 10001
>>>
>>> Once you?ve defined the group the way you want you can then create a
>>> nodeset from it.
>>>
>>> Sorry if I haven?t really answered your question, but I think I need
>>> some more details on what you?re trying to do.
>>>
>>> Cheers, Charles
>>>
>>>
>>>
>>>> On 24/11/2014, at 7:05 am, Sauber-Rosenber, Jeanne M. (GSFC-6980)
>>>> <jeanne.m.sauber-rosenberg at nasa.gov> wrote:
>>>>
>>>> A number of us spoke briefly with Brad at the Stanford workshop
>>>> about expanding (3D/hex) step18 & step 19 (one surface load at 0,0)
>>>> to input multiple loads. IF I would like to input a variable
>>>> surface load over a portion of the positive Z face, I believe Brad
>>>> suggested creating a separate subdomain/nodeset on the +z face (?)
>>>> In CUBIT, do I create first the +z node set (CUBIT commands in
>>>> step 1 below) and then I create a subset by removing nodes outside
>>>> a center region (incomplete CUBIT command in step 2 below)?
>>>>
>>>> If I should create a subset of the z+ surface to input surface
>>>> loads commands: 1. Do I need to input a load at every point in the
>>>> subdomain to be able to use linear interpolation? 2. Do you put the
>>>> 0 tractions on the edges of this subdomain or on the edges of
>>>> +z-face, i.e. such as in the step 19 example given in the
>>>> spatialdb/tractions_axial_pressure.spatialdb file?
>>>>
>>>> I tried but never succeeded in creating a subdomain in CUBIT.
>>>>
>>>> Step 1: #
>>>> ----------------------------------------------------------------------
>>>>
>>>>
>> # Create node set for +z face
>>>> #
>>>> ----------------------------------------------------------------------
>>>> group "face_zpos" add node in surface 1 nodeset 16 group
>>>> face_zpos nodeset 16 name "face_zpos"
>>>>
>>>> Step 2:
>>>> #-----------------------------------------------------------------------
>>>>
>>>>
>> #create nodeset for load/unload set
>>>> #-----------------------------------------------------------------------
>>>>
>>>>
>> what OTHER commands?
>>>> nodeset 17 in surface all with x_coord > 10001 remove nodeset 17 in
>>>> surface all with x_coord < -10001 remove nodeset 17 in surface all
>>>> with y_coord > 10001 remove nodeset 17 in surface all with
>>>> y_coord < -10001 remove
>>>>
>>>> Thanks, Jeanne Sauber
>>>> _______________________________________________ CIG-SHORT mailing
>>>> list CIG-SHORT at geodynamics.org
>>>> http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-short
>>>
>>> Charles A. Williams Scientist GNS Science 1 Fairway Drive, Avalon PO
>>> Box 30368 Lower Hutt 5040 New Zealand ph (office): 0064-4570-4566
>>> fax (office): 0064-4570-4600 C.Williams at gns.cri.nz
>>>
>>> _______________________________________________ CIG-SHORT mailing
>>> list CIG-SHORT at geodynamics.org
>>> http://lists.geodynamics.org/cgi-bin/mailman/listinfo/cig-short
>>>
>>
>>
>>
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>>
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>> End of CIG-SHORT Digest, Vol 98, Issue 25
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>
>
>
> --
> 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
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Charles A. Williams
Scientist
GNS Science
1 Fairway Drive, Avalon
PO Box 30368
Lower Hutt 5040
New Zealand
ph (office): 0064-4570-4566
fax (office): 0064-4570-4600
C.Williams at gns.cri.nz
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