[Nek5000-users] Pipe with expansion
nek5000-users at lists.mcs.anl.gov
nek5000-users at lists.mcs.anl.gov
Sat Jan 18 12:26:08 CST 2014
Hi Paul,
I looked at the Helix and stenosis example but they are using cosine functions to deform
I tried to use a tangent function but it bends the whole pipe.
I dint look at peris example .
I will take a look at it and let you know.
Thank you
Kamal
On Jan 18, 2014, at 7:22 PM, nek5000-users at lists.mcs.anl.gov wrote:
>
> Kamal,
>
> Have you looked at the peris example? The usr file there shows how to deform
> a pipe geometry.
>
> 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: Saturday, January 18, 2014 12:17 PM
> To: nek5000-users at lists.mcs.anl.gov
> Subject: Re: [Nek5000-users] Pipe with expansion
>
> Dear Paul,
>
> I tried many ways to map my straight pipe geometry but it does not seem to work properly
>
> I used something like
>
> X = X + Z * tan ( alpha )
> Y = Y + Z* tan (alpha )
>
>
> even that dint work. could please help me with this
>
> Thank you
>
> Kamal.
>
> On Jan 17, 2014, at 2:24 PM, nek5000-users at lists.mcs.anl.gov wrote:
>
>> Hi Paul,
>>
>> Thanks paul. I tried working with the diverging mesh modification.
>>
>> I tried to use this form of equation to modify the mesh
>>
>> z = mx + b
>> z = ny + c
>>
>> x = ( z - b ) / m
>> y = (z - c) / n
>>
>> Do you think would work ? or is there any other way to input that ?
>>
>> Thanks,
>>
>> Kamal
>>
>>
>> On 17/01/2014 14:14, nek5000-users at lists.mcs.anl.govwrote:
>>> 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 ofnek5000-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
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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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>>
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