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

JR Cary cary at txcorp.com
Wed Jul 22 17:30:12 EDT 2015


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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