[Nek5000-users] Linearised Navier Stokes

Thu Aug 17 13:23:38 CDT 2017

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> 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:
>
> 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> 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 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>
>>> 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 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.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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