[Nek5000-users] SYM boundary conditions

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

Yes, it is turbulent...

I will try to use ON. Please, could you help me to understand a bit more 
why it could work?

Thanks again!
Cheers
SL


El 10-02-2016 12:17, nek5000-users at lists.mcs.anl.gov escribió:
> one initial suggestion would be to use ON at the outflow. Is the flow
> turbulent at the outflow boundary?
> Philipp
> 
> On 2016-02-10 11:45, nek5000-users at lists.mcs.anl.gov wrote:
>> Hi,
>> 
>> Thank you. I am trying to simulate a flow whose inlet boundary 
>> condition
>> is time periodic ux=sin(omega*time). Since there is an injection and a
>> suction, and the mean flow is zero, I think that the boundary 
>> conditions
>> should let the transpiration/penetration of the flow... (I have tried 
>> to
>> run the simulation using outflow BC but it crashes). Is there any BC
>> condition in Nek5000 that suits to this problem?
>> 
>> Thank you for your help in advance.
>> Best regards,
>> SL
>> 
>> El 10-02-2016 10:20, nek5000-users at lists.mcs.anl.gov escribió:
>>> Hi,
>>> SYM is essentially means that the velocity through the interface is
>>> zero and for the inplane velocities that the normal gradients vanish.
>>> So it does not allow transpiration/penetration through the boundary.
>>> So I suspect that this condition is not what you are looking for.
>>> 
>>> However, I am not exactly sure what you really mean. Perhaps you can
>>> say a bit more about your case?
>>> 
>>> Best regards,
>>> Philipp
>>> 
>>> On 2016-02-10 08:02, nek5000-users at lists.mcs.anl.gov wrote:
>>>> Hi Neks,
>>>> 
>>>> I am looking for a boundary condition that leads the flow to go out 
>>>> or
>>>> to go into the domain.
>>>> 
>>>> Is 'SYM' valid for this purpose?
>>>> 
>>>> 
>>>> I think that what I am looking for is, in the outlet surface:
>>>> 
>>>>    - If the velocity vector at the outlet points out of the domain, 
>>>> then
>>>> the boundary condition for the velocity will be of the Neumann type
>>>> 
>>>>    - However, if the velocity at the outlet points into the domain, 
>>>> then
>>>> we can imagine that the outflow is no longer an outflow, but an 
>>>> inflow,
>>>> and that we therefore would like to specify a Dirichlet boundary
>>>> condition for velocity
>>>> 
>>>> 
>>>> Thanks in advance
>>>> SL
>>>> 
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>> 
>> 
>> 
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