[Nek5000-users] WSS on several processors

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

Hi Paul,

Yes, torq_calc generates integral quantities, viscous drag (dragvx, dragvy,
dragvz) for example. You are right, my issue is different: I defined an
object, which is a cylindric pipe's wall, with set_obj; and now I' m trying
to find all the coordinates of this object and quantities dg(1,2), dg(2,2),
dg(3,2) in these coordinates. My code works fine for the serial setting but
with parallel setting only a part of coordinates is dumped into the file.
And this part corresponds to the values of one CPU (I run my case with 16
CPU on one node). I have tried to use subroutine gop(x, w op, n) but it
doesn't work.


Best regards, Andrew



2016-07-11 18:58 GMT+02:00 <nek5000-users at lists.mcs.anl.gov>:

>
> Hi Andrew,
>
> torq_calc (which also computes drag as a byproduct) will generate integral
> quantities over several
> objects.
>
> So, you could have (say) the upper and lower wall as two separate objects,
> and you can get the
> drag on each.   This amounts to 2 vector quantities (3 numbers each:
>  fx,fy,fz) at each time step
> and is written out by node 0.
>
> It sounds like you are asking for something different, e.g., the wall
> shear stress as a function of
> position --- that requires a bit more sophistication but is certainly
> accessible.
>
> What are you looking for?
>
> Best, Paul
>
> ------------------------------
> *From:* nek5000-users-bounces at lists.mcs.anl.gov [
> nek5000-users-bounces at lists.mcs.anl.gov] on behalf of
> nek5000-users at lists.mcs.anl.gov [nek5000-users at lists.mcs.anl.gov]
> *Sent:* Sunday, July 10, 2016 12:39 PM
> *To:* nek5000-users at lists.mcs.anl.gov
> *Subject:* [Nek5000-users] WSS on several processors
>
> Hi Neks,
>
> I am working with two routines (torq_calc and drgtrq )in navier5.f. I'm
> trying  to collect viscous drag's values on the wall (in all the grid
> points) and write them into a file. If I run a calculation on the one CPU
> it works great, but it doesn't work with several processors: I have an
> impression that the information is written into result file from only one
> processors. How can I fix this problem?
>
> Thank you for any suggestion,
> Andrew
>
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