[Nek5000-users] Linearised Navier Stokes
nek5000-users at lists.mcs.anl.gov
nek5000-users at lists.mcs.anl.gov
Fri Aug 18 10:26:05 CDT 2017
Hi clio,
Thank you for the suggestion. I have got the base flow now. But when I
tried to run the perturbation using the sample .par file for the dfh_cav
case for a different problem, the base flow is getting tmestepped instead
of perturbation. I have used the same .par file from the dfh_cav case and
has used the follwoing settings:
[PROBLEMTYPE]
perturbations = yes
solveBaseflow = no
variableProperties = yes
Can you please let me know where I may be mistaken.
Swarandeep
On Fri, Aug 18, 2017 at 3:32 PM, <nek5000-users at lists.mcs.anl.gov> wrote:
> Hi Swarandeep,
>
> The binary mesh is saved in the re2 file, you can use that file to
> generate a map file with genmap.
>
> You don't need to start from the box file, because for this specific case
> the type of the boundary conditions is the same for the linear and
> nonlinear simulations.
>
> Regards,
>
> clio
>
>
> Quoting nek5000-users at lists.mcs.anl.gov:
>
> Hi
>> I could no find the ###.ma2 file for the dfh_cav example. Hence I
>> suppose I require the ###.box or the ###.map file to proceed for the base
>> flow. Please correct me if I have misunderstood.
>>
>> Swarandeep
>>
>> On Fri, Aug 18, 2017 at 1:03 AM, <nek5000-users at lists.mcs.anl.gov> wrote:
>>
>> Hi Swarandeep,
>>>
>>> For computing the base flow you can use the same mesh and map file. What
>>> you need to change is 1) the boundary conditions such that they are valid
>>> for the base flow and 2) the flags that you run a nonlinear instead of a
>>> linear case.
>>>
>>> As Clio was saying, in that particular case the base flow was computed
>>> using a Newton method. For lower Rayleigh numbers, you should however be
>>> able to just run (nonlinear) DNS to reach the steady state.
>>>
>>> Best regards,
>>> Philipp
>>>
>>> On 2017-08-17 20:23, nek5000-users at lists.mcs.anl.gov wrote:
>>>
>>> Hi Clio and Adam,
>>>>
>>>> Thanks for the information.
>>>>
>>>> I think in order to compute the base flow I need the ###.box file as
>>>> well as a different ###.usr file as I think the boundary and initial
>>>> conditions for the ###.usr file in the short_tests/dfh_cav directory is
>>>> applicable for the perturbations only. Please send me the ###.box and
>>>> the
>>>> corresponding ###.usr file applicable for the base flow for dfh_cav
>>>> case.
>>>>
>>>> Swarandeep
>>>>
>>>>
>>>> On Thu, Aug 17, 2017 at 7:03 PM, <nek5000-users at lists.mcs.anl.gov
>>>> <mailto:nek5000-users at lists.mcs.anl.gov>> wrote:
>>>>
>>>> Hi Swarandeep,
>>>>
>>>> The baseflow has been computed with a Newton solver (which is not
>>>> available in the nek examples). The additional code had been
>>>> implemented in the version 1040 of nek5000, and there is no .par
>>>> file for that. However, in general, if your case is laminar, to
>>>> compute a baseflow, you just need to evaluate the steady state of
>>>> your nonlinear case. For that, you can use the same .par file, and
>>>> just change to the nonlinear solver (perturbationmodes = 0,
>>>> perturbations = no, solveBaseflow = yes).
>>>>
>>>> The non dimensionalization is based on Hellums and Churchill (1962).
>>>>
>>>> The equations are:
>>>>
>>>> Pr (du/dt + (U*nabla)u + (u*nabla)U) = 1/sqrt(Ra)laplacian(u) -grad
>>>> p + e_g theta
>>>> d theta/dt + (u*nabla)Theta + (U*nabla)theta =
>>>> 1/sqrt(Ra)laplacian(theta)
>>>> div(u)=0
>>>>
>>>> where u, theta are respectively the velocity and temperature of the
>>>> perturbation, U, Theta the velocity and temperature of the baseflow.
>>>>
>>>> You can find more information in the paper "Saglietti, Clio, et al.
>>>> "Adjoint optimization of natural convection problems: differentially
>>>> heated cavity." Theoretical and Computational Fluid Dynamics (2016):
>>>> 1-17." on which the example is based.
>>>>
>>>> Regards,
>>>>
>>>> clio
>>>>
>>>>
>>>> Quoting nek5000-users at lists.mcs.anl.gov
>>>> <mailto:nek5000-users at lists.mcs.anl.gov>:
>>>>
>>>> Hi Adam,
>>>>
>>>> Thanks for the clarification. Can you please send me a sample
>>>> .par file for
>>>> the baseflow for the case of "dfh_cav". Also is it possible to
>>>> get the
>>>> equations solved for this problem(dfh_cav). I would like to know
>>>> the way
>>>> that this has been made dimensionless.
>>>>
>>>> For your kind information I briefly describe my case which I
>>>> have been used
>>>> to solve with the regular non-linear framework using older
>>>> versions (.rea
>>>> files). My setup is as follows:
>>>> Geometry is a 3D cylindrical annullus.
>>>> Temperature are fixed at inner and outer cylinders.
>>>> Gravity is acting in -z direction
>>>> There is a back ground rotation which is constant.
>>>>
>>>> Please let me know if any other info is required. Thanks for the
>>>> help.
>>>>
>>>> Swarandeep
>>>>
>>>>
>>>>
>>>>
>>>> On Thu, Aug 17, 2017 at 1:48 PM,
>>>> <nek5000-users at lists.mcs.anl.gov
>>>> <mailto:nek5000-users at lists.mcs.anl.gov>> wrote:
>>>>
>>>> Hi Swarandeep,
>>>>
>>>> Yes. You generate ###.rea in the standard way. In the old
>>>> version it was
>>>> txt and contained both mesh information and runtime
>>>> parameter. One could
>>>> split mesh information (###.re2, binary file) and runtime
>>>> parameters
>>>> (###.rea with negative number of elements or currently
>>>> ###.par) using
>>>> reatore2 tool. The map file is generated with genmap (can be
>>>> txt or
>>>> binary). So the procedure is more or less the same. If you
>>>> have ###.rea
>>>> with mesh you split it and generate ###.re2. Next you
>>>> generate ###.map with
>>>> genmap and finally ###.par by hand. Be careful to use tolls
>>>> from the same
>>>> release, as they've been changed significantly (e.g. binary
>>>> ###.map file).
>>>> Regards
>>>> Adam
>>>>
>>>>
>>>> On 16/08/17 18:52, nek5000-users at lists.mcs.anl.gov
>>>> <mailto:nek5000-users at lists.mcs.anl.gov> wrote:
>>>>
>>>> Hi Adam,
>>>>
>>>> Thank you very much for the help.
>>>>
>>>> Does the ###.map, ###.box file and from them the
>>>> ###.rea file
>>>> (in the dfh_cav case: the ###.re2 files) are created as
>>>> done for the
>>>> earlier versions i.e., by using genbox and genmap. Please
>>>> clarify.
>>>>
>>>> Swarandeep
>>>>
>>>>
>>>>
>>>> On Wed, Aug 16, 2017 at 5:35 PM,
>>>> <nek5000-users at lists.mcs.anl.gov
>>>> <mailto:nek5000-users at lists.mcs.anl.gov>> wrote:
>>>>
>>>> Hi,
>>>>
>>>> The simplest way would be to look into existing example
>>>> under
>>>> Nek5000/short_test/dfh_cav/
>>>> It is a differentially heated cavity case and covers
>>>> both direct and
>>>> adjoint linear solver. It is compatible with the current
>>>> git version and
>>>> uses ###.par file instead of ###.rea.
>>>> Regards
>>>> Adam
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> On 11/08/17 11:05, nek5000-users at lists.mcs.anl.gov
>>>> <mailto:nek5000-users at lists.mcs.anl.gov> wrote:
>>>>
>>>> This information might be outdated (old version) but
>>>> previously the base
>>>> flow was read in using the restart option in the rea
>>>> file. The disturbance
>>>> you can read in yourself in userchk.
>>>>
>>>> Philipp
>>>>
>>>> On 2017-08-11 10:49, nek5000-users at lists.mcs.anl.go
>>>> v
>>>> <mailto:nek5000-users at lists.mcs.anl.gov> wrote:
>>>>
>>>> Hi Philipp,
>>>>
>>>> That was very much helpful. I have a
>>>> steady base flow and
>>>> temperature state. Please let me know where to
>>>> provide the base flow.
>>>>
>>>>
>>>> Thank you
>>>> Swarandeep
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