[Nek5000-users] Outflow Boundary Condition Clarification

[nek5000-users at lists.mcs.anl.gov]

Attached is a .usr with turb_outflow that works for this case---there is

no difficulty if you use the prescribed input values, as shown in the attached

files.


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.


http://mcs.anl.gov/~obabko/jet_vm.mpeg


This mesh is a bit under-resolved in the z-direction.

The files for a new case, with more axial resolution, are posted here


www.mcs.anl.gov/~fischer/jet2.tgz<http://www.mcs.anl.gov/~fischer/jet2.tgz>


I'll be posting an example with a script on how to build this geometry to nekexamples soon.


Paul


________________________________
From: Nek5000-users <nek5000-users-bounces at lists.mcs.anl.gov> on behalf of nek5000-users at lists.mcs.anl.gov <nek5000-users at lists.mcs.anl.gov>
Sent: Friday, February 2, 2018 1:10:32 PM
To: nek5000-users at lists.mcs.anl.gov
Subject: [Nek5000-users] Outflow Boundary Condition Clarification

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?

--
Nitish Kovalam
Aerospace Engineering
Indian Institute of Space Science and Technology
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