[Nek5000-users] Pipe with expansion

nek5000-users at lists.mcs.anl.gov nek5000-users at lists.mcs.anl.gov
Mon Jan 20 14:36:30 CST 2014


Hi Paul, 

Thanks and that helped.

Where can I find the variables like Turbulent KE , shear stress on the wall. ? 

Do i have to activate some parameters for calculating them ?

If I had to plot them.

Thanks, 
Kamal 


On Jan 20, 2014, at 5:41 AM, nek5000-users at lists.mcs.anl.gov wrote:

> 
> Kamal,
> 
> Looks good.
> 
> I'm guessing that one further refinement would be:
> 
> if (z.gt.z0) scale = 1 + (smax-1)*(z-z0)/(z1-z0)
> if (z.gt.z1) scale = smax
> 
> which would yield
> 
>   scale = 1 when z=z0
>   scale = smax when z >= z1
> 
> Paul
> 
> 
> 
> On Sun, 19 Jan 2014, nek5000-users at lists.mcs.anl.gov wrote:
> 
>> Hi paul,
>> 
>> The code works fine, but there should be a small change thats has to be done
>> 
>> 
>> if (z.gt.z0) scale = 1 + (z /(z1-z0 )))
>> if (z.gt.z1) scale = smax
>> 
>> This creates a perfect diverging pipe.
>> 
>> Thanks for the help paul.
>> 
>> Kamal
>> 
>> On Jan 20, 2014, at 12:09 AM, nek5000-users at lists.mcs.anl.gov wrote:
>> 
>>> Hi paul,
>>> 
>>> If I am not wrong,
>>> I make a mesh with three straight pipes( inlet, divergent, outlet ) connected together via n2to3 so that I know the element connectivity places of the divergent section (z0,z1) and use the section what you gave
>>> 
>>> Thank you for the code
>>> 
>>> Kamal
>>> 
>>> On Jan 19, 2014, at 8:45 PM, nek5000-users at lists.mcs.anl.gov wrote:
>>> 
>>>> 
>>>> 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
>>>>>>>>> https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users
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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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