[visit-developers] 2d meshes and 3d vectors

sveta sveta at txcorp.com
Wed Jul 22 19:33:58 EDT 2015


Hi Mark,
We find many cases when we need a 3d vector on a 2d mesh (all curls, 
cross products etc).
Thanks,
Sveta

On 7/22/15 3:30 PM, JR Cary wrote:
> Hi Mark,
>
> I guess this was mostly answered, but we often restrict simulations
> to 2D because of size, but all three components of the vector field
> are needed.  E.g., laser-plasma interactions, we would like to see
> the 3-vector of E on the 2D mesh.
>
> Indeed curl E-3-vector exists, i.e., dEz/dx ~ dBy/dt.
>
> John
>
> On 7/22/15 2:30 PM, Miller, Mark C. wrote:
>> Hi Sveta,
>>
>> Hmm. I see the picture and think I understand the meaning of 3D
>> vectors on a 2D mesh.
>>
>> I am just trying to understand what the source of that data is?
>> Where's it comming from? Whats driving the condition of having 2D mesh
>> data with vectors defined on the mesh that have a 3rd component?
>> Ordinarily, for purely 2D problems, only 2D entities make mathematical
>> sense. If you are taking curls of vectors in 2D, then the magnitude of
>> the result can be thought of as a component of a vector out of the 2D
>> plane but that is really just a conceptual convenience
>> (hxxps://www.physicsforums.com/threads/curl-in-2d-is-a-vector-or-a-scalar.745388/).
>> Its really a scalar value that you wind up with. You don't all of the
>> sudden wind up adding a 3rd dimension to a setting which was
>> originally purely 2D. This is the reason for my question…why do you
>> have 3D vectors on a 2D mesh to begin with?
>>
>> From: sveta <sveta at txcorp.com <mailto:sveta at txcorp.com>>
>> Reply-To: "visit-developers at elist.ornl.gov
>> <mailto:visit-developers at elist.ornl.gov>"
>> <visit-developers at elist.ornl.gov <mailto:visit-developers at elist.ornl.gov>>
>> Date: Wednesday, July 22, 2015 1:16 PM
>> To: "visit-developers at elist.ornl.gov
>> <mailto:visit-developers at elist.ornl.gov>"
>> <visit-developers at elist.ornl.gov <mailto:visit-developers at elist.ornl.gov>>
>> Subject: Re: [visit-developers] 2d meshes and 3d vectors
>>
>>     Hi Mark,
>>     These are vectors sticking into the 3d dimension sitting on a 2d
>>     thing
>>     (see attached).  Yes, the mesh is 2d meaning that there are only x
>>     and y
>>     values.
>>     Thanks,
>>     S
>>
>>     On 7/22/15 2:10 PM, Miller, Mark C. wrote:
>>
>>         First, wanna make sure what you mean by 2d mesh. You have a
>>         mesh in
>>         which z coord is always zero? If so, yeah, VisIt won't let you
>>         have
>>         vectors on that mesh with more than two components. If you
>>         don't have
>>         option of applying an operator of some kind (like transform with
>>         x-rotate by a tiny fraction of a degree), then probably best
>>         thing is to
>>         accomodate this in the plugin.
>>
>>         Out of curiosity thoug, can you describe the use case for 3D
>>         vectors on
>>         a 2D mesh? It might be best if we ultimately get rid of the
>>         constraints
>>         prohibiting this in VisIt.
>>
>>         Mark
>>
>>
>>         From: Sveta <sveta at txcorp.com <mailto:sveta at txcorp.com>
>>         <mailto:sveta at txcorp.com> <mailto:sveta at txcorp.com%3E>>
>>         Reply-To: "visit-developers at elist.ornl.gov
>>         <mailto:visit-developers at elist.ornl.gov>
>>         <mailto:visit-developers at elist.ornl.gov>
>>         <mailto:visit-developers at elist.ornl.gov%3E>"
>>         <visit-developers at elist.ornl.gov
>>         <mailto:visit-developers at elist.ornl.gov>
>>         <mailto:visit-developers at elist.ornl.gov>
>>         <mailto:visit-developers at elist.ornl.gov%3E>>
>>         Date: Wednesday, July 22, 2015 12:49 PM
>>         To: "visit-developers at elist.ornl.gov
>>         <mailto:visit-developers at elist.ornl.gov>
>>         <mailto:visit-developers at elist.ornl.gov>
>>         <mailto:visit-developers at elist.ornl.gov%3E>"
>>         <visit-developers at elist.ornl.gov
>>         <mailto:visit-developers at elist.ornl.gov>
>>         <mailto:visit-developers at elist.ornl.gov>
>>         <mailto:visit-developers at elist.ornl.gov%3E>>
>>         Subject: [visit-developers] 2d meshes and 3d vectors
>>
>>              Hi everybody,
>>
>>              What is the best way to be able to deal with 3d vectors
>>         and their
>>              magnitudes, when the mesh is 2d?
>>
>>              I could check in Vs plugin for this and create a 3d mesh
>>         if the the
>>              vector has 3 components.  But is there a better way?  Can
>>         I set a mesh
>>              dimensionality through some function call of VisIt?  I
>>         cannot not go
>>              interactively through elevate operator as we have
>>         embeddded VisIt in
>>              our
>>              application.
>>
>>              Thank you,
>>              SVeta
>>
>>
>>
>



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