[Nek5000-users] Pipe with expansion
nek5000-users at lists.mcs.anl.gov
nek5000-users at lists.mcs.anl.gov
Mon Jan 20 14:52:04 CST 2014
Hi Kamal,
You'll need to compute your own tke by manipulating the
velocity fields.
You can get running averages of the requisite quantities
via calls to "avg_all" which is found in navier5.f
You can compute shear stress on the wall simply by computing
the drag on the wall, which can be done via a call to torque_calc(),
also found in navier5.f
If you cd to /examples and type:
grep torq */*.usr
you'll find many examples of calls to torque_calc. You simply
need to prescribe the surfaces on which shear is to be integrated.
I typically write a routine "set_obj" to identify such surfaces
on the first call to usrchk.
grep set_obj */*.usr
will show similar examples.
I would recommend trying this for laminar Poiseiulle flow in
a very simple channel just to check that your calls are properly
set.
Best,
Paul
On Mon, 20 Jan 2014, nek5000-users at lists.mcs.anl.gov wrote:
> 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
>>>>>>>>>> _______________________________________________
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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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