[Nek5000-users] tubChannel - neknek script

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

Hi Marco,

The number of elements is set in .rea file. Only the maximum number of elements allowed is set in SIZE file. So, as long as your number of elements set in SIZE larger than a number of elements in each of your sub-domains, you are good to go. This is a generic set-up for neknek problems. TurbChannel example is slightly different in a sense that it hardwires the number of elements in .usr file to be used with post-processing. If you need to follow this approach, yes, putting if statements in the .usr file would perhaps help. 

Hope it helps.

Yulia




On Mar 21, 2017, at 9:15 AM, nek5000-users at lists.mcs.anl.gov wrote:

> Hello,
> 
> I am running the neknek script with the turbChannel example. My setup consists of two channels: the first one has periodic boundary conditions, and the second one has inlet/outlet boundary conditions. The numerical solution of first channel is used as an inlet condition for the second channel. The numerical solution seems to behave as expected. 
> 
> My next step is to simulate a short channel with periodic boundary conditions, and a longer one with inlet/outlet boundary conditions. The number of elements in the streamwise direction (x-axis) now differs. This is causing some problems since the number of elements in the x,y and z directions are set in the SIZE file that is unique to the sessions named inside and outside. Note that I need the number of elements in each direction to compute the y+ and u+ values.
> 
> In the turbChannel example, the number of elements in the x, y and z directions are defined in the usr file (nelx, nely and nelz). This approach could work in my case, I think, assuming that I include a if statement on the session name (inside vs outside). However, I am after something more generic that can be applied to more complex geometries where the number of elements in each direction is not known or difficult to know. 
> 
> Is there a way with Nek5000 to get the number of elements in each direction in a automated way?
> 
> I have another question that is a little bit off topic: when initializing an array in the subroutines defined in the usr file, should I use nelv or lelv as the number of elements per processors? In the turbChannel example, both are used and it confuses me. nelv is the maximum number of elements per processor, whereas lelv is the actual number of elements in a processor, which leads me to think lelv should be used. Is this correct?
> 
> Thanks,
> 
> Marco
> 
> 
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