[Nek5000-users] Integral on the wall

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

Dear Paul,

using the subroutine in zfunc.f I got the value of the pressure averaged on the surface. However I would like to compute the force on the wall as the line integral of the pressure times the normal (maybe my first question was unclear). Do you think this can be achieved modifying a bit the subroutine in zfunc.f or should I do it from scratch?

Thanks. Best,


Valerio

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Da: Nek5000-users <nek5000-users-bounces at lists.mcs.anl.gov> per conto di nek5000-users at lists.mcs.anl.gov <nek5000-users at lists.mcs.anl.gov>
Inviato: mercoledì 9 maggio 2018 15:11
A: nek5000-users at lists.mcs.anl.gov
Oggetto: Re: [Nek5000-users] Integral on the wall


Dear Paul,


Thank you for the help, I will test the routine zfunc.


Best,

Valerio

________________________________
Da: Nek5000-users <nek5000-users-bounces at lists.mcs.anl.gov> per conto di nek5000-users at lists.mcs.anl.gov <nek5000-users at lists.mcs.anl.gov>
Inviato: mercoledì 9 maggio 2018 15:05
A: nek5000-users at lists.mcs.anl.gov
Oggetto: Re: [Nek5000-users] Integral on the wall



Dear Valerio,


I've not tested or even compiled the attached code...


But it should be fairly close to being functional.


The idea would be to pass in the pressure on mesh 1, which

means you need to interpolate from pr to pm1 ---- there are

several routines floating around to do this.


Please let me know if you have any questions and if you

are able to make this routine work.


Best,

Paul


PS - note that you should be able to send in "zm1" to this

routine and get back the correct z distribution.  This is what

I would do if I wished to plot pr vs z.   Also, you might want

to dsavg() pm1 if you want a continuous pressure estimate.



________________________________
From: Nek5000-users <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: Wednesday, May 9, 2018 5:55:29 AM
To: nek5000-users at lists.mcs.anl.gov
Subject: Re: [Nek5000-users] Integral on the wall



Dear Valerio,


You would need to modify torque calc to do this,

assuming that your objective is to compute a line

integral of the pressure on the GLL points.


Assuming that your pipe mesh was made by

sweeping the geometry in the z direction with

n2to3, the modification should be quite easy.


The routine I would start with would be drgtrq

in navier5.f, which I see uses the two-index

loop to traverse faces based on jskip1 and jskip2.


For your case, I would use the facind() 3 index

loop approach (e.g., as used in norcmp2 routine).


Then you track the outer "k" loop and accumulate one

value for each k value and for each z level of the elements.

You will know the z level because it will be:


   klevel_e = 1 + (eg-1)/nelxy


where nelxy is the number of elements in your pipe

cross section.


Hopefully this will get you pointed in the right direction...


Best,

Paul




________________________________
From: Nek5000-users <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: Wednesday, May 9, 2018 3:13:19 AM
To: nek5000-users at lists.mcs.anl.gov
Subject: [Nek5000-users] Integral on the wall


Dear all,

I want to compute the integral of the pressure on pipe wall at different cross-sections. I tried using the routine set_obj, setting as many objects as the number of elements along the pipe length and then using the routine torque_calc. However I would like to compute it on each circumference where GLL nodes are defined, for example if I use lx1 = 8 I would like to compute it on 8 cross-sections per element. Is there an efficient way to do this using the set_obj routine?


Thanks. Best regards.

Valerio
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