[Nek5000-users] Sponge/Dong boundary condition: Nek5000-users Digest, Vol 109, Issue 2

Mon Mar 12 12:39:55 CDT 2018

Hi Daniel,
I can send you the code if you contact me by email. Unfortunately, I 
haven't had the time to prepare a proper example that works with newer 
versions.

PHilipp

On 2018-03-12 17:17, nek5000-users at lists.mcs.anl.gov wrote:
> Hi Phillip,
> 
> 
> Apologies for the delayed reply, seeing your code and implementation of 
> the Dong boundary condition would be very useful.  I may also have a 
> look at the Appelquist paper but at this point I would just like 
> something that allows my flow to leave the domain without crashing the 
> simulation.
> 
> 
> Thanks for your help.
> 
> 
> Best,
> 
> 
> Daniel
> 
> 
> 
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> *To:* nek5000-users at lists.mcs.anl.gov
> *Subject:* Nek5000-users Digest, Vol 109, Issue 2
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> Today's Topics:
> 
>     1. Re: Sponge layer in Nek5000 (nek5000-users at lists.mcs.anl.gov)
>     2. Re: Sponge layer in Nek5000 (nek5000-users at lists.mcs.anl.gov)
> 
> 
> ----------------------------------------------------------------------
> 
> Message: 1
> Date: Thu, 1 Mar 2018 12:24:45 -0700
> From: nek5000-users at lists.mcs.anl.gov
> To: nek5000-users at lists.mcs.anl.gov
> Subject: Re: [Nek5000-users] Sponge layer in Nek5000
> Message-ID:
>          <mailman.9875.1519932288.19102.nek5000-users at lists.mcs.anl.gov>
> Content-Type: text/plain; charset="utf-8"
> 
> Hi Daniel,
> 
> We did implement the Sponge layer a couple of years back in nek5000 at the
> outflow boundary condition. We used a Smagorinsky type of eddy-viscosity
> closure where the Smagorinsky coefficient quadratically varies in the x
> direction (where is the direction of dominant flow), close to a few
> elements near the outflow. You can set it up with uservp in nek5000.
> However, the stabilized natural outflow boundary conditions by Dong et al.
> (2014) behaves much better than the sponge layer in my opinion. For my type
> of problem the sponge layer actually creates artificial diffusive
> structures close to the boundary, even when they are applied very smoothly,
> and you need to chop off the near-outflow region for data analysis.
> 
> On Thu, Mar 1, 2018 at 9:56 AM, <nek5000-users at lists.mcs.anl.gov> wrote:
> 
>> Hi all,
>>
>>
>> I'm trying to implement outflow boundary conditions for a turbulent plume
>> using a sponge layer to absorb the energy of the flow and prevent
>> reflections back into the domain.  I was wondering whether there is
>> anything set up in Nek already to construct this sponge layer or if it's
>> something I need to do myself, and if so whether anybody could help with
>> something they've done before - I've read a couple of other threads here
>> that mention a sponge layer but not its implementation.
>>
>>
>> I look forward to hearing from you.
>>
>>
>> Best,
>>
>>
>> Daniel Ward
>>
>> _______________________________________________
>> Nek5000-users mailing list
>> Nek5000-users at lists.mcs.anl.gov
>> https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users
>>
>>
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> Message: 2
> Date: Thu, 1 Mar 2018 22:05:45 +0100
> From: nek5000-users at lists.mcs.anl.gov
> To: nek5000-users at lists.mcs.anl.gov
> Subject: Re: [Nek5000-users] Sponge layer in Nek5000
> Message-ID:
>          <mailman.9881.1519938356.19102.nek5000-users at lists.mcs.anl.gov>
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> 
> Hi,
> we have also implemented various sponges and other boundary conditions,
> including the Dong condition and convective conditions. The sponge we
> typically base on a "direct" forcing approach as e.g. described in the
> paper by Appelquist (JFM 2015); the implementation of that type of
> forcing is in userf.
> 
> The Dong condition is essentially a modified "o" condition (where one
> has to change a few lines here and there in the code, but I could send
> you our code), and the convective condition, which behaved the best (see
> e.g. the Master's thesis by Erik Bostr?m) can be implemented in
> usercheck. The latter condition did create the least upstream disturbances.
> 
> Philipp
> 
> On 2018-03-01 20:24, nek5000-users at lists.mcs.anl.gov wrote:
>> Hi Daniel,
>> 
>> We did implement the Sponge layer a couple of years back in nek5000 at 
>> the outflow boundary condition. We used a Smagorinsky type of 
>> eddy-viscosity closure where the Smagorinsky coefficient quadratically 
>> varies in the x direction (where is the direction of dominant flow), 
>> close to a few elements near the outflow. You can set it up with uservp 
>> in nek5000. However, the stabilized natural outflow boundary conditions 
>> by Dong et al. (2014) behaves much better than the sponge layer in my 
>> opinion. For my type of problem the sponge layer actually creates 
>> artificial diffusive structures close to the boundary, even when they 
>> are applied very smoothly, and you need to chop off the near-outflow 
>> region for data analysis.
>> 
>> On Thu, Mar 1, 2018 at 9:56 AM, <nek5000-users at lists.mcs.anl.gov 
>> <mailto:nek5000-users at lists.mcs.anl.gov>> wrote:
>> 
>>     Hi all,
>> 
>> 
>>     I'm trying to implement outflow boundary conditions for a turbulent
>>     plume using a sponge layer to absorb the energy of the flow and
>>     prevent reflections back into the domain.? I was wondering whether
>>     there is anything set up in Nek already to construct this sponge
>>     layer or if it's something I need to do myself, and if so whether
>>     anybody could help with something they've done before - I've read a
>>     couple of other threads here that mention a sponge layer but not its
>>     implementation.
>> 
>> 
>>     I look forward to hearing from you.
>> 
>> 
>>     Best,
>> 
>> 
>>     Daniel Ward
>> 
>> 
>>     _______________________________________________
>>     Nek5000-users mailing list
>>     Nek5000-users at lists.mcs.anl.gov <mailto:Nek5000-users at lists.mcs.anl.gov>
>>     https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users
>>     <https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users>
>> 
>> 
>> 
>> 
>> _______________________________________________
>> Nek5000-users mailing list
>> Nek5000-users at lists.mcs.anl.gov
>> https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users
>> 
> 
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