[Nek5000-users] About the iobj in the drag calculation

[nek5000-users at lists.mcs.anl.gov]

Hi Xianbei,

You can define more objects by picking your
own surface discriminators (which will 
be dependent on your particular application).

If you need more than 4 objects, you can increase maxobj
in SIZE.

Typically, dragx(0) would be the sum of the drag on all
the objects --- this is sometimes useful.

If you have (say) a 4-sided channel, you can just define
one object instead of 4, and set it to be the collection
of all faces for which cbc(f,e,1)='W  '.

Paul



On Thu, 29 May 2014, nek5000-users at lists.mcs.anl.gov wrote:

> Hi,all:
     I read Paul's reply in this mail https://lists.mcs.anl.gov/mailman/htdig/nek5000-users/2014-May/002756.html
     And got to know something about objects. As you say, the object is a collection of faces, here , I have a question about the iboj, how could I know which face it represent with iboj? As in turbChannel.usr,
      dragx_avg = alpha*dragx_avg + beta*0.5*(dragx(1)+dragx(2))
      I think it means to do the time-average of the average dragx on planey1 and planey2, as
      0.5*(dragx(1)+dragx(2))
  indicates, while how to calculate the dragx on the planex1, planex2, planez1 and planez2? for the maxobj in this example is only 4 and dragx is defined as
      dragx(0:maxobj)

Thank you
Xianbei