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

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

Thank you, I know the urms/u_tau**2 is to rescale the data, but why

(urms_pl(i)-(uavg_pl(i))**2)
but the other components are not? I mean minus the uavg_pl(i).









At 2014-05-29 06:56:56, nek5000-users at lists.mcs.anl.gov wrote:
>
>These are just rescalings of turbulent fluctuations
>in terms of wall units, which allows them to be compared with
>other data in the literature.
>
>
>
>On Thu, 29 May 2014, nek5000-users at lists.mcs.anl.gov wrote:
>
>> Hi,
>     I'm sorry to trouble. I find these lines in set_obj subroutine
>             if (f.eq.1) iobj=1  ! lower wall
>             if (f.eq.3) iobj=2  ! upper wall
>     so this defines which wall to be represented. Another question comes that why the urms is calculate like
>     do i=1,m
>                 write(56,3) yy(i)+1
>      &                     ,(yy(i)+1)*Re_tau
>      &                     , (urms_pl(i)-(uavg_pl(i))**2)/u_tau**2
>      &                     , vrms_pl(i)/u_tau**2
>      &                     , wrms_pl(i)/u_tau**2
>      &                     , uvms_pl(i)/u_tau**2
>                 write(57,3)  yy(i) + 1.
>      &                     , (yy(i)+1.)*Re_tau
>      &                     , uavg_pl(i)/u_tau
>     3           format(1p15e17.9)
>             enddo
>
>As can be seen,R_uu=(urms_pl(i)-(uavg_pl(i))**2)/u_tau**2, while R_vv=vrms_pl(i)/u_tau**2,why?
>
>
>
>
>
>
>在 2014-05-29 02:24:34，nek5000-users at lists.mcs.anl.gov 写道：
>
>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
>
>
>
>
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