[Nek5000-users] Pipe with expansion
nek5000-users at lists.mcs.anl.gov
nek5000-users at lists.mcs.anl.gov
Fri Jan 17 07:14:51 CST 2014
Kamal,
1) To check for convergence, run your simulation for increasing polynomial
orders ( lx1 in the SIZE file) and measure some consistent quantity (drag,
TKE, etc). You can plot this quantity against lx1 and this should give you
a good picture of how you are converging (without needing to change the
physical mesh).
2) If you weren't using temperature in your simulation, you could do put
the following code snippet in your userchk
c-------------------------------------------
integer i, ntot
ntot = nx1*ny1*nz1*nelv ! total number of points in simulation (on THIS
processor)
do i = 1,ntot
t(i,1,1,1,1) = 0.5*(vx(i,1,1,1)**2 + vy(i,1,1,1)**2 + vz(i,1,1,1)**2)
enddo
ifto = .true.
c-------------------------------------------
I've assumed here that your density is unity. This computed kinetic energy
point-wise and stores it in the temperature field. The part "ifto =
.true." tells Nek to output the temperature field whenever it outputs a
field file. You could then view this in visit just like you would the
velocity field.
Hope this helps!
Josh
On Wed, Jan 15, 2014 at 9:52 AM, <nek5000-users at lists.mcs.anl.gov> wrote:
> Hi Paul,
>
> I will try that mapping, I created a straight pipe to do some simulations.
>
> 1) Is there a way to check my spectral convergence, so that I can do some
> mesh convergence study?
> 2) Is there a way to plot the kinetic energy in the flow ?
>
> Thank you,
> Kamal
>
>
>
>
> On 15/01/2014 12:14, nek5000-users at lists.mcs.anl.gov wrote:
>
>>
>> Hi Kamal,
>>
>> For the geometry you describe, I would apply mesh morphing
>> to a standard straight pipe. You can create such a pipe
>> using a subset of the mkmesh script provided in the expansion
>> example.
>>
>> If your transition region is conical, then I woud make
>> certain that the change in slope occurs at element boundaries,
>> i.e., as in the half cross-section depicted below:
>>
>> _______________
>> /| | |
>> / | | |
>> /| | | |
>> ________________/ | | | |
>> | | | | | | | |
>> | | | | | | | |
>> +-----+-----+---+--+---+------+------+----> z
>>
>>
>> Paul
>>
>>
>>
>> On Wed, 15 Jan 2014, nek5000-users at lists.mcs.anl.gov wrote:
>>
>> Hi Paul,
>>>
>>> I looked at the example and it looks very helpful, but for a sudden
>>> expansion we have only two parts (i.e) the inlet pipe and the outlet pipe.
>>> Whereas in a diverging pipe we have three section (i.e,) The inlet pipe,
>>> Diverging section and the outlet pipe.
>>>
>>>
>>> Is it possible for me to create a 2D diverging section using mesh
>>> modification and revolve it around the centre axis to get a 3d diverging
>>> pipe ?
>>>
>>>
>>> or should I apply the mesh modification directly to the 3d sudden
>>> expansion pipe using usrdat2() ?
>>>
>>> Thanks,
>>> Kamal
>>>
>>>
>>> On 14/01/2014 21:09, nek5000-users at lists.mcs.anl.gov wrote:
>>>
>>>> Hi Paul,
>>>>
>>>> Thanks a lot for the update. I will take a look at as soon as possible
>>>> and keep you updated with it.
>>>>
>>>> Thank you,
>>>>
>>>> Kamal
>>>>
>>>> On Jan 14, 2014, at 9:04 PM, nek5000-users at lists.mcs.anl.gov wrote:
>>>>
>>>> Kamal,
>>>>>
>>>>> I've added an example for a step-type expansion in a pipe. New example
>>>>> directory
>>>>> is nek5_svn/examples/expansion, with a README.
>>>>>
>>>>> If you want a standard diffuser, I would use mesh-morphing, as
>>>>> outlined in the
>>>>> nek primer, which can be found on this page:
>>>>>
>>>>> http://nek5000.mcs.anl.gov/index.php/UG#Documentation
>>>>>
>>>>> I've also automated our turbulent outflow bc treatment -- one simply
>>>>> provides an
>>>>> expansion factor (typically ~ 1.5) and two persistent arrays to
>>>>> turb_outflow(), which
>>>>> is now in navier5.f. This can be useful when very strong vortices
>>>>> are leaving the
>>>>> domain, which is possible for certain diffuser flow conditions (and
>>>>> others).
>>>>>
>>>>> 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: Monday, January 13, 2014 3:35 AM
>>>>> To: nek5000-users at lists.mcs.anl.gov
>>>>> Subject: [Nek5000-users] Creating a Mesh
>>>>>
>>>>> Hi
>>>>>
>>>>> Can some one please help me in this because I am new to nek
>>>>>
>>>>> 1) How can I create a .rea for a specific geometry say ' A sudden
>>>>> expansion pipe ' or a ' Diverging pipe '
>>>>>
>>>>> 2) What tool I should use to create that mesh.
>>>>>
>>>>>
>>>>> Thank you
>>>>>
>>>>>
>>>>> kamal
>>>>> _______________________________________________
>>>>> Nek5000-users mailing list
>>>>> Nek5000-users at lists.mcs.anl.gov
>>>>> https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users
>>>>> _______________________________________________
>>>>> Nek5000-users mailing list
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>>>>>
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>
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--
Josh Camp
"All that is necessary for the triumph of evil is that good men do nothing"
-- Edmund Burke
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