[Nek5000-users] Nek5000-users Digest, Vol 111, Issue 3

Sat May 5 22:47:04 CDT 2018

Dear Jian,

Did you look a long time average of the scale factor?

It does fluctuate over time when the flow is turbulent.

Perhaps you got it at the wrong time, or perhaps there

is something about your configuration that we're not

understanding (though I have no idea of what that

could possibly be at this point).

Are you running with variable viscosity or anything

like that?

This approach normally provides the correct ffz value.

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: Saturday, May 5, 2018 10:25:36 AM
To: nek5000-users at lists.mcs.anl.gov
Subject: Re: [Nek5000-users] Nek5000-users Digest, Vol 111, Issue 3

Hello Paul and Ketan,

I really appreciate your reply. Do you mean the third column which is 1.56E-02, is the ffz force if para(54) and para(55) are 0?

To be honest, I tried a case that 1.56E-02 was used as ffz in the usr file while setting para(54) and (55) are 0. The case was set to start from where keeping flowrate stopped which have the right mean velocities. But the mean streamwise velocity decreased a lot. So I am wondering how much ffz should be.

       1 0.1617415E+03  1.56161E-02  1.22442E-07  7.85399E-01  7.85399E-01 volflow Z
       2 0.1617415E+03  1.56215E-02  9.51058E-08  7.85399E-01  7.85399E-01 volflow Z
       3 0.1617415E+03  1.56186E-02  9.08498E-08  7.85399E-01  7.85399E-01 volflow Z
       4 0.1617415E+03  1.56207E-02  1.09035E-07  7.85399E-01  7.85399E-01 volflow Z
       5 0.1617416E+03  1.56204E-02  1.30839E-07  7.85399E-01  7.85399E-01 volflow Z
       6 0.1617416E+03  1.56200E-02  1.57003E-07  7.85399E-01  7.85399E-01 volflow Z
       7 0.1617416E+03  1.56198E-02  1.88400E-07  7.85399E-01  7.85399E-01 volflow Z
       8 0.1617417E+03  1.56196E-02  2.26078E-07  7.85399E-01  7.85399E-01 volflow Z

Kind regards,

Jian

On 4 May 2018 at 18:00, <nek5000-users-request at lists.mcs.anl.gov<mailto:nek5000-users-request at lists.mcs.anl.gov>> wrote:
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Today's Topics:

   1. Re: ffx ffy ffz from current run (nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov>)
   2. Re: ffx ffy ffz from current run (nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov>)
   3. Postprocessing: Append data to output file
      (nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov>)
   4. Re: Postprocessing: Append data to output file
      (nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov>)

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Message: 1
Date: Thu, 3 May 2018 17:36:06 +0000
From: nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov>
To: "nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov>"
        <nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov>>
Subject: Re: [Nek5000-users] ffx ffy ffz from current run
Message-ID:
        <mailman.841.1525368969.86639.nek5000-users at lists.mcs.anl.gov<mailto:mailman.841.1525368969.86639.nek5000-users at lists.mcs.anl.gov>>
Content-Type: text/plain; charset="utf-8"

Hi Jian,

Not exactly sure what you mean, but if you are using p54, p55 to set your flowrate, then you can use your logfile to get what the corresponding forcing should be using ffx/ffy/ffz.

As per drive2.f, if you are using param(54),param(55), then in logfile you can grep for ?volflow?, and ?scale? represents the ffx/ffy/ffz.

      if (nio.eq.0) write(6,1) istep,chv(icvflow)
     $   ,scale,delta_flow,current_flow,flow_rate
    1    format(i11,'  volflow ',a1,11x,1p4e13.4)

c     Note, this scale factor corresponds to FFX, provided FFX has
c     not also been specified in userf.   If ffx is also specified
c     in userf then the true FFX is given by ffx_userf + scale.

Ketan

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Message: 2
Date: Thu, 3 May 2018 23:03:18 +0000
From: nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov>
To: "nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov>"
        <nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov>>
Subject: Re: [Nek5000-users] ffx ffy ffz from current run
Message-ID:
        <mailman.860.1525388608.86639.nek5000-users at lists.mcs.anl.gov<mailto:mailman.860.1525388608.86639.nek5000-users at lists.mcs.anl.gov>>
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Dear Zhai,

Assuming you have a periodic domain in direction "d" (d=1,2,3 or x,y,z), and

that you have ffx=ffy=ffz=0 in your .usr file, then

grep volf logfile

will show a list of time step, time, and "ffd" + other columns.

Column 3 will be "ffd"

where ffd is the force in the direction "d" and d = |p54|.

p54 = +/-  1  ==>   d=x direction

           +/-  2 ==>         y direction

           +/-  3 ==>         z direction

If p54 < 0, then p55 determines the mean velocity in direction d

If p54 > 0, then p55 determines the volumetric flux in direction d

(Note that p55 < 0 would be the flow is in the reverse direction.)

hth,

Paul

________________________________
From: Nek5000-users <nek5000-users-bounces at lists.mcs.anl.gov<mailto:nek5000-users-bounces at lists.mcs.anl.gov>> on behalf of nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov> <nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov>>
Sent: Thursday, May 3, 2018 11:47:44 AM
To: nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov>
Subject: [Nek5000-users] ffx ffy ffz from current run

Hi Nek users,

How can I get the ffx ffy and ffz from the simulation with flowrate fixed, where ffx ffy and ffz are in usr file?

Kind regards,

Zhai
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Message: 3
Date: Fri, 4 May 2018 06:39:25 +0000
From: nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov>
To: "nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov>"
        <nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov>>
Subject: [Nek5000-users] Postprocessing: Append data to output file
Message-ID:
        <mailman.885.1525415969.86639.nek5000-users at lists.mcs.anl.gov<mailto:mailman.885.1525415969.86639.nek5000-users at lists.mcs.anl.gov>>
Content-Type: text/plain; charset="iso-8859-1"

Hi,

I am postprocessing output files in order to compute the vorticity.

So far I have followed the instructions in https://lists.mcs.anl.gov/pipermail/nek5000-users/2010-March/000171.html,

where it is explained how to output the vorticity components as velocity components.

I however would like to make a simultaneous visualization of the vorticity field, the velocity field and some of the scalar fields.

If postprocessing a file "mycase0.f000XX" - is it then possible to append the vorticity to this file?

If this is not possible, how would I to in order to write the velocity and the vorticity in the same file?

The interface of the subroutine outpost is outpost(vx,vy,vz,pr,t,nam), but I have 3 scalars in addition to the temperature.

How can I write a file containing both the vorticity and the four scalar fields?

Best,

Johan
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Message: 4
Date: Fri, 4 May 2018 11:30:41 +0200
From: nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov>
To: nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov>     <nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov>>
Subject: Re: [Nek5000-users] Postprocessing: Append data to output
        file
Message-ID:
        <mailman.888.1525426277.86639.nek5000-users at lists.mcs.anl.gov<mailto:mailman.888.1525426277.86639.nek5000-users at lists.mcs.anl.gov>>
Content-Type: text/plain; charset="utf-8"

Assuming you are using par, define a scalar:

[SCALAR01] # vorticity
solver = none

Then, just store the vorticity in t(1,1,1,1,iscal +1) where iscal is your passive scalar index (in this example 1).

On 4 May 2018, at 08:39, "nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov> <mailto:nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov>> " <nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov> <mailto:nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov>> > wrote:

Hi,