Re: [yt-users] velocity fields in yt
Although actually, "RadialVelocity" is one place where it would also be an issue. It doesn't look like that is corrected for Zeus, if x-velocity etc are still face-centred. Am I reading that right? Elizabeth Tasker wrote:
I was wondering if the x-velocity, y-velocity and z-velocity fields themselves had been averaged to give a cell-centred quantity. There's no need for them to be so, I just needed to know before I calculated a cross-product to find the rotational potential of clouds I'd picked out.
Thank you for the clarification :)
Elizabeth
Matthew Turk wrote:
Only in the DivV and VoritictySquared fields. Where else should it be made?
On Wed, Aug 3, 2011 at 5:04 PM, Elizabeth Tasker <taskere@mcmaster.ca> wrote:
Hi,
Quick question about the baryon velocity fields in yt: has any correction been made for the fact Zeus uses face-centred, not cell-centred, velocities?
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Yes, it could be off by 0.5*dx. To calculate it correctly, do you need to center the velocity field by re-filling boundary values? On Wed, Aug 3, 2011 at 5:23 PM, Elizabeth Tasker <taskere@mcmaster.ca> wrote:
Although actually, "RadialVelocity" is one place where it would also be an issue. It doesn't look like that is corrected for Zeus, if x-velocity etc are still face-centred. Am I reading that right?
Elizabeth Tasker wrote:
I was wondering if the x-velocity, y-velocity and z-velocity fields themselves had been averaged to give a cell-centred quantity. There's no need for them to be so, I just needed to know before I calculated a cross-product to find the rotational potential of clouds I'd picked out.
Thank you for the clarification :)
Elizabeth
Matthew Turk wrote:
Only in the DivV and VoritictySquared fields. Where else should it be made?
On Wed, Aug 3, 2011 at 5:04 PM, Elizabeth Tasker <taskere@mcmaster.ca> wrote:
Hi,
Quick question about the baryon velocity fields in yt: has any correction been made for the fact Zeus uses face-centred, not cell-centred, velocities?
Elizabeth _______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
_______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
_______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
_______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
Maybe a similar scheme to that used for _DivV? So centre the velocity field by averaging the two face values in the appropriate direction within def _RadialVelocity? Ideally, I guess bulk_velocity would also be calculated using cell-centred quantities, but I think that is set by the user? In which case, it's up to them to decide whether to include the off-set (which for a large object is probably negligible). Matthew Turk wrote:
Yes, it could be off by 0.5*dx. To calculate it correctly, do you need to center the velocity field by re-filling boundary values?
On Wed, Aug 3, 2011 at 5:23 PM, Elizabeth Tasker <taskere@mcmaster.ca> wrote:
Although actually, "RadialVelocity" is one place where it would also be an issue. It doesn't look like that is corrected for Zeus, if x-velocity etc are still face-centred. Am I reading that right?
Elizabeth Tasker wrote:
I was wondering if the x-velocity, y-velocity and z-velocity fields themselves had been averaged to give a cell-centred quantity. There's no need for them to be so, I just needed to know before I calculated a cross-product to find the rotational potential of clouds I'd picked out.
Thank you for the clarification :)
Elizabeth
Matthew Turk wrote:
Only in the DivV and VoritictySquared fields. Where else should it be made?
On Wed, Aug 3, 2011 at 5:04 PM, Elizabeth Tasker <taskere@mcmaster.ca> wrote:
Hi,
Quick question about the baryon velocity fields in yt: has any correction been made for the fact Zeus uses face-centred, not cell-centred, velocities?
Elizabeth _______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
_______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
_______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
_______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
_______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
Hi Elizabeth, I'm not quite sure what your question is at this point. Maybe you should just report back when you've had a chance to work a bit on the 0.5*dx? j On Wed, Aug 3, 2011 at 2:52 PM, Elizabeth Tasker <taskere@mcmaster.ca> wrote:
Maybe a similar scheme to that used for _DivV? So centre the velocity field by averaging the two face values in the appropriate direction within def _RadialVelocity?
Ideally, I guess bulk_velocity would also be calculated using cell-centred quantities, but I think that is set by the user? In which case, it's up to them to decide whether to include the off-set (which for a large object is probably negligible).
Matthew Turk wrote:
Yes, it could be off by 0.5*dx. To calculate it correctly, do you need to center the velocity field by re-filling boundary values?
On Wed, Aug 3, 2011 at 5:23 PM, Elizabeth Tasker <taskere@mcmaster.ca> wrote:
Although actually, "RadialVelocity" is one place where it would also be an issue. It doesn't look like that is corrected for Zeus, if x-velocity etc are still face-centred. Am I reading that right?
Elizabeth Tasker wrote:
I was wondering if the x-velocity, y-velocity and z-velocity fields themselves had been averaged to give a cell-centred quantity. There's no need for them to be so, I just needed to know before I calculated a cross-product to find the rotational potential of clouds I'd picked out.
Thank you for the clarification :)
Elizabeth
Matthew Turk wrote:
Only in the DivV and VoritictySquared fields. Where else should it be made?
On Wed, Aug 3, 2011 at 5:04 PM, Elizabeth Tasker <taskere@mcmaster.ca> wrote:
Hi,
Quick question about the baryon velocity fields in yt: has any correction been made for the fact Zeus uses face-centred, not cell-centred, velocities?
Elizabeth _______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
_______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
_______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
_______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
_______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
_______________________________________________ yt-users mailing list yt-users@lists.spacepope.org http://lists.spacepope.org/listinfo.cgi/yt-users-spacepope.org
participants (3)
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Elizabeth Tasker -
j s oishi -
Matthew Turk