Hello all, I looked through the previous threads on yt-users, and I don't see this particular problem described. Hoping for some help. So, the quantity dark_matter_density is a CIC-deposited particle quantity, which becomes a grid field. I would like to do something like this: for every grid voxel, calculate the mean dm particle *velocity* inside that voxel return as a grid field Is that simple using CIC_deposit? The only mean particle velocity I've seen used in yt/enzo before is the one calculated for halos, by using HOP or FOF identification. thanks! Eric
Hi Eric, (Thanks for re-sending.) On Fri, Aug 26, 2011 at 3:31 PM, Eric Hallman <hallman13@gmail.com> wrote:
Hello all, I looked through the previous threads on yt-users, and I don't see this particular problem described. Hoping for some help. So, the quantity dark_matter_density is a CIC-deposited particle quantity, which becomes a grid field. I would like to do something like this: for every grid voxel, calculate the mean dm particle *velocity* inside that voxel return as a grid field Is that simple using CIC_deposit? The only mean particle velocity I've seen used in yt/enzo before is the one calculated for halos, by using HOP or FOF identification. thanks!
This has been done in the past for fields like the mean stellar metallicity. In that case, cic_deposit was used to deposit both the total mass in metals and the total mass in particles, then they were divided. What I would recommend you do is copy the logic in that field, but modify it to deposit a velocity-multiplied-by-mass, and then divide by the total deposited mass. Hope that helps, Matt
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Hi Eric, Just to add to what Matt said, the code and examples for doing this are in yt/frontends/enzo/fields.py. The function _star_field is used to calculate mass-weighted grid fields for just the star particles using the CIC_deposit. In that function, you should see two calls to cic_deposit. The first is with a field that is the product of the desired field and the mass field, and the second is just for the mass field. Then dividing them gives the mass-weighted field. Below that, there are some examples of fields being created that use this function. It looks like all you have to do is name the field correctly and the _star_field function figures out which particle data it should be using (i.e, metallicity, creation time, etc.) Britton On Fri, Aug 26, 2011 at 9:46 PM, Matthew Turk <matthewturk@gmail.com> wrote:
Hi Eric,
(Thanks for re-sending.)
Hello all, I looked through the previous threads on yt-users, and I don't see this particular problem described. Hoping for some help. So, the quantity dark_matter_density is a CIC-deposited particle quantity, which becomes a grid field. I would like to do something like this: for every grid voxel, calculate the mean dm particle *velocity* inside
On Fri, Aug 26, 2011 at 3:31 PM, Eric Hallman <hallman13@gmail.com> wrote: that
voxel return as a grid field Is that simple using CIC_deposit? The only mean particle velocity I've seen used in yt/enzo before is the one calculated for halos, by using HOP or FOF identification. thanks!
This has been done in the past for fields like the mean stellar metallicity. In that case, cic_deposit was used to deposit both the total mass in metals and the total mass in particles, then they were divided. What I would recommend you do is copy the logic in that field, but modify it to deposit a velocity-multiplied-by-mass, and then divide by the total deposited mass.
Hope that helps,
Matt
Eric _______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
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