[Nek5000-users] Linearised Navier Stokes

nek5000-users at lists.mcs.anl.gov nek5000-users at lists.mcs.anl.gov
Fri Aug 18 07:40:39 CDT 2017


Hi Adam,

      Thank you for the continued support. I managed to get the base flow
and then I used it in a perturbation calculation following the dfh_cav
case. Peculiarly, I an finding that the basic state is getting time stepped
and the perturbations are not (in contrast to the dfh_cav case). 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 am am mistaken.

Swarandeep



On Fri, Aug 18, 2017 at 4:52 PM, <nek5000-users at lists.mcs.anl.gov> wrote:

> Hi,
>
> ###.ma2 is the binary version of ###.map file and you need only one of
> them (it is a new feature). The map (or ma2) is generated by travis during
> testing by running genmap, so we do not keep it in repository.
> regards
> adam
>
>
> On 18/08/17 10:49, nek5000-users at lists.mcs.anl.gov wrote:
>
> 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.gov
>>>                     <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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