<div dir="ltr">Thank you Paul and Phillip for such a quick reply. I will run the jet case attached. So why was there no such problem when the first vortex from the wake of a circular cylinder was leaving the domain? <br></div><div class="gmail_extra"><br><div class="gmail_quote">On Sat, Feb 3, 2018 at 1:49 AM, <span dir="ltr"><<a href="mailto:nek5000-users-request@lists.mcs.anl.gov" target="_blank">nek5000-users-request@lists.mcs.anl.gov</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Send Nek5000-users mailing list submissions to<br>
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Today's Topics:<br>
<br>
1. Outflow Boundary Condition Clarification<br>
(<a href="mailto:nek5000-users@lists.mcs.anl.gov">nek5000-users@lists.mcs.anl.<wbr>gov</a>)<br>
2. Re: Outflow Boundary Condition Clarification<br>
(<a href="mailto:nek5000-users@lists.mcs.anl.gov">nek5000-users@lists.mcs.anl.<wbr>gov</a>)<br>
3. Re: Outflow Boundary Condition Clarification<br>
(<a href="mailto:nek5000-users@lists.mcs.anl.gov">nek5000-users@lists.mcs.anl.<wbr>gov</a>)<br>
<br>
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<br>
Message: 1<br>
Date: Sat, 3 Feb 2018 00:40:32 +0530<br>
From: <a href="mailto:nek5000-users@lists.mcs.anl.gov">nek5000-users@lists.mcs.anl.<wbr>gov</a><br>
To: <a href="mailto:nek5000-users@lists.mcs.anl.gov">nek5000-users@lists.mcs.anl.<wbr>gov</a><br>
Subject: [Nek5000-users] Outflow Boundary Condition Clarification<br>
Message-ID:<br>
<<a href="mailto:mailman.7741.1517598636.19102.nek5000-users@lists.mcs.anl.gov">mailman.7741.1517598636.<wbr>19102.nek5000-users@lists.mcs.<wbr>anl.gov</a>><br>
Content-Type: text/plain; charset="utf-8"<br>
<br>
Im trying to simulate the formation of shear layer when a jet exits a<br>
nozzle and enters the flow domain. As the FIRST vortex leaves the outlet (<br>
at which I have provided 'O' boundary condition using genbox) the solution<br>
diverges. I tried to implement the 'turbulent outflow' subroutine as<br>
suggested in the forum but now the vortex affects the upstream flow. But<br>
when I run the flow past circular cylinder example, the vortices leave the<br>
domain without any issue even though only 'O' boundary condition is used'.<br>
What is the difference between the two cases and what can i do to prevent<br>
the issue?<br>
<br>
--<br>
Nitish Kovalam<br>
Aerospace Engineering<br>
Indian Institute of Space Science and Technology<br>
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Message: 2<br>
Date: Fri, 2 Feb 2018 20:27:50 +0100<br>
From: <a href="mailto:nek5000-users@lists.mcs.anl.gov">nek5000-users@lists.mcs.anl.<wbr>gov</a><br>
To: <a href="mailto:nek5000-users@lists.mcs.anl.gov">nek5000-users@lists.mcs.anl.<wbr>gov</a><br>
Subject: Re: [Nek5000-users] Outflow Boundary Condition Clarification<br>
Message-ID:<br>
<<a href="mailto:mailman.7745.1517601585.19102.nek5000-users@lists.mcs.anl.gov">mailman.7745.1517601585.<wbr>19102.nek5000-users@lists.mcs.<wbr>anl.gov</a>><br>
Content-Type: text/plain; charset=utf-8; format=flowed<br>
<br>
I think you should try the stabilised O condition, as described in a<br>
paper by Dong (2014). We have an implementation of that, we should<br>
probably provide it as a module in the repository.<br>
<br>
best regards,<br>
Philipp<br>
<br>
On 2018-02-02 20:10, <a href="mailto:nek5000-users@lists.mcs.anl.gov">nek5000-users@lists.mcs.anl.<wbr>gov</a> wrote:<br>
> Im trying to simulate the formation of shear layer when a jet exits a<br>
> nozzle and enters the flow domain. As the FIRST vortex leaves the outlet<br>
> ( at which I have provided 'O' boundary condition using genbox) the<br>
> solution diverges. I tried to implement the 'turbulent outflow'<br>
> subroutine as suggested in the forum but now the vortex affects the<br>
> upstream flow. But when I run the flow past circular cylinder example,<br>
> the vortices leave the domain without any issue even though only 'O'<br>
> boundary condition is used'. What is the difference between the two<br>
> cases and what can i do to prevent the issue?<br>
><br>
> --<br>
> Nitish Kovalam<br>
> Aerospace Engineering<br>
> Indian Institute of Space Science and Technology<br>
><br>
><br>
> ______________________________<wbr>_________________<br>
> Nek5000-users mailing list<br>
> <a href="mailto:Nek5000-users@lists.mcs.anl.gov">Nek5000-users@lists.mcs.anl.<wbr>gov</a><br>
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<br>
Message: 3<br>
Date: Fri, 2 Feb 2018 20:19:54 +0000<br>
From: <a href="mailto:nek5000-users@lists.mcs.anl.gov">nek5000-users@lists.mcs.anl.<wbr>gov</a><br>
To: "<a href="mailto:nek5000-users@lists.mcs.anl.gov">nek5000-users@lists.mcs.anl.<wbr>gov</a>"<br>
<<a href="mailto:nek5000-users@lists.mcs.anl.gov">nek5000-users@lists.mcs.anl.<wbr>gov</a>><br>
Subject: Re: [Nek5000-users] Outflow Boundary Condition Clarification<br>
Message-ID:<br>
<<a href="mailto:mailman.7749.1517602797.19102.nek5000-users@lists.mcs.anl.gov">mailman.7749.1517602797.<wbr>19102.nek5000-users@lists.mcs.<wbr>anl.gov</a>><br>
Content-Type: text/plain; charset="us-ascii"<br>
<br>
<br>
Attached is a .usr with turb_outflow that works for this case---there is<br>
<br>
no difficulty if you use the prescribed input values, as shown in the attached<br>
<br>
files.<br>
<br>
<br>
Here is a movie of the result - you can see that turb_outflow is turned on prior to the jet reaching the top of the domain.<br>
<br>
<br>
<a href="http://mcs.anl.gov/~obabko/jet_vm.mpeg" rel="noreferrer" target="_blank">http://mcs.anl.gov/~obabko/<wbr>jet_vm.mpeg</a><br>
<br>
<br>
This mesh is a bit under-resolved in the z-direction.<br>
<br>
The files for a new case, with more axial resolution, are posted here<br>
<br>
<br>
<a href="http://www.mcs.anl.gov/~fischer/jet2.tgz" rel="noreferrer" target="_blank">www.mcs.anl.gov/~fischer/jet2.<wbr>tgz</a><<a href="http://www.mcs.anl.gov/~fischer/jet2.tgz" rel="noreferrer" target="_blank">http://www.mcs.anl.gov/~<wbr>fischer/jet2.tgz</a>><br>
<br>
<br>
I'll be posting an example with a script on how to build this geometry to nekexamples soon.<br>
<br>
<br>
Paul<br>
<br>
<br>
______________________________<wbr>__<br>
From: Nek5000-users <<a href="mailto:nek5000-users-bounces@lists.mcs.anl.gov">nek5000-users-bounces@lists.<wbr>mcs.anl.gov</a>> on behalf of <a href="mailto:nek5000-users@lists.mcs.anl.gov">nek5000-users@lists.mcs.anl.<wbr>gov</a> <<a href="mailto:nek5000-users@lists.mcs.anl.gov">nek5000-users@lists.mcs.anl.<wbr>gov</a>><br>
Sent: Friday, February 2, 2018 1:10:32 PM<br>
To: <a href="mailto:nek5000-users@lists.mcs.anl.gov">nek5000-users@lists.mcs.anl.<wbr>gov</a><br>
Subject: [Nek5000-users] Outflow Boundary Condition Clarification<br>
<br>
Im trying to simulate the formation of shear layer when a jet exits a nozzle and enters the flow domain. As the FIRST vortex leaves the outlet ( at which I have provided 'O' boundary condition using genbox) the solution diverges. I tried to implement the 'turbulent outflow' subroutine as suggested in the forum but now the vortex affects the upstream flow. But when I run the flow past circular cylinder example, the vortices leave the domain without any issue even though only 'O' boundary condition is used'. What is the difference between the two cases and what can i do to prevent the issue?<br>
<br>
--<br>
Nitish Kovalam<br>
Aerospace Engineering<br>
Indian Institute of Space Science and Technology<br>
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</blockquote></div><br><br clear="all"><br>-- <br><div class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr">Nitish Kovalam<div>Aerospace Engineering</div><div>Indian Institute of Space Science and Technology</div></div></div>
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