[Nek5000-users] Pipe with expansion
nek5000-users at lists.mcs.anl.gov
nek5000-users at lists.mcs.anl.gov
Fri Jan 17 07:24:38 CST 2014
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.gov wrote:
> 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
> <mailto: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
> <mailto: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
> <mailto: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
> <mailto: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
> <mailto: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
> <mailto:nek5000-users-bounces at lists.mcs.anl.gov>
> [nek5000-users-bounces at lists.mcs.anl.gov
> <mailto:nek5000-users-bounces at lists.mcs.anl.gov>]
> on behalf of nek5000-users at lists.mcs.anl.gov
> <mailto:nek5000-users at lists.mcs.anl.gov>
> [nek5000-users at lists.mcs.anl.gov
> <mailto:nek5000-users at lists.mcs.anl.gov>]
> Sent: Monday, January 13, 2014 3:35 AM
> To: nek5000-users at lists.mcs.anl.gov
> <mailto: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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