[Nek5000-users] NekNek with PN-PN

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

Dear Paul and Yulia,

Thank you very much for your responses. Regarding you comments,

1. I do not have any outflow boundary conditions in my simulations.

2. Coupling pressure in Pn/Pn-2 works fine for laminar flows, but once I 
get into the turbulent regime, the extrapolation used to map pressure to 
GLL points causes some trouble. I pass pressure from domain-1 to 
domain-2, and works on the gradient of pressure in domain-2. I see 
clearly the oscillations of pressure gradient at the element boundaries. 
(please see the attachment)

Could you please give hints on how can I run neknek with PN/PN?

Thanks once again,

Best regards,
Sudhakar



On 03/30/2017 01:37 AM, nek5000-users at lists.mcs.anl.gov wrote:
> That’s correct. Neknek is not currently implemented with Pn/Pn formulation. However, there are some ways around it if you use outflow boundary conditions instead of interpolation at the outflow boundaries. I am not sure if this example is in repo, but it should be doable, if this is what you need.
>
> Yulia
>
>
> On Mar 29, 2017, at 4:10 AM, nek5000-users at lists.mcs.anl.gov wrote:
>
>> Dear Nek users,
>>
>> I am coupling Navier-Stokes and Darcy equations using NekNek. I need to pass pressure from Navier-Stokes as the boundary condition for Darcy equation. Pn/Pn-2 formulations extrapolate pressure to GLL nodes and apply dsavg to compute C-0 continuous pressure field. Though the resulting pressure field is continuous it is not very smooth and exhibits oscillations near each element boundaries. Using this as the boundary condition for Darcy equation gives raise to convergence issues after some time steps. I tried to use neknek with Pn/Pn formulation which will avoid this problem. However, I endup with "ERROR: .... crs_solve: invalid handle" and the simulation breaks away after the first time step in "happy_check" subroutine.
>>
>> Is Neknek not implemented for Pn/Pn formulations?
>>
>> Thank you very much for your response,
>>
>> Best regards,
>> Sudhakar
>> Linne FLOW centre.
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