[CIG-SHORT] CIG-SHORT Digest, Vol 98, Issue 25

Tue Nov 25 05:33:25 PST 2014

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.

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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