[Nek5000-users] Pipe with expansion
nek5000-users at lists.mcs.anl.gov
nek5000-users at lists.mcs.anl.gov
Sun Jan 19 13:45:05 CST 2014
Kamal,
I would do the following in usrdat2():
n=nx1*ny1*nz1*nelt
do i=1,n
x=xm1(i,1,1,1)
y=ym1(i,1,1,1)
z=ym1(i,1,1,1)
scale = 1.
if (z.gt.z0) scale = smax*(z-z0/(z1-z0)
if (z.gt.z1) scale = smax
xm1(i,1,1,1) = scale*x
ym1(i,1,1,1) = scale*y
enddo
Paul
Make certain that z1 and z0 correspond to z values
that precisely coincide with element interfaces.
On Sun, 19 Jan 2014, nek5000-users at lists.mcs.anl.gov wrote:
> Hi Paul,
>
> I looked into the Peris example but It is so what same like the stenosis example with a Cosine deformation.
>
> In my case it is a pipe with conical divergent. I tried to play around the variables Xm1, Ym1 and Zm1 but the mapping doesn't go well.
>
> Could you please help me with this.
>
> Thank you,
>
> Kamal
>
>
> On Jan 18, 2014, at 7:26 PM, nek5000-users at lists.mcs.anl.gov wrote:
>
>> 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
>>>>> _______________________________________________
>>>>> Nek5000-users mailing list
>>>>> Nek5000-users at lists.mcs.anl.gov
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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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