[yt-users] Define a derived field of disk surface density

[Matthew Turk]

Hi Suoqing,

If I understand correctly, you want to compute the *local* surface
density (i.e., the integrated density up to that height) for each
cell?  As in, re you defining it such that it's a function of r,
theta, z, or are you computing the surface density *once* for a disk
object and using that (i.e., function of r, theta)?

-Matt

On Tue, Mar 18, 2014 at 2:24 AM, Suoqing JI <suoqing at physics.ucsb.edu> wrote:
> Hi,
>
> I'm working on FLASH 3D Cartesian AMR data, and would like to define a
> derived field of surface density, so I can use surface density field to
> calculate other derived fields.
>
> My current script does give desired results (slice_y:
> http://i.imgur.com/XigIYJc.png   slice_z: http://i.imgur.com/kA2Fmlt.png,
> and the disk is cut from original data). However, it's extremely
> inefficient, because I cast a ray through disk height for every cells
> located on x-y plane surface of each AMR block.
>
> So is there any clever way to define surface density as a derived field in
> YT, as what the figures attached show? Or some way without defining surface
> density as a derived field, but I can get access to surface density values
> when computing other derived fields?
>
> Thanks a lot!
>
> Best wishes,
> --
> Suoqing JI
> Ph.D Student
> Department of Physics
> University of California, Santa Barbara
> CA 93106, USA
>
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