[Nek5000-users] Warning Message : L1/L2 DIV(V)

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

The WARNING tells you that the divergence of your flow field is too large. It's hard to say why this happens because there are many possible reasons (wrong bc, resolution to low, timestep to large, etc.). 

I agree in your case the thermal divergence is ZERO. In your case the norms of div(v) and div(v)-qtl should be the same because qtl=0.

Do you add some divergence to the outflow boundary? In this case the user specified divergence will be stored using qtl. 


Stefan

On May 3, 2010, at 9:56 PM, nek5000-users at lists.mcs.anl.gov wrote:

> Dear Developers,
> 
> I am trying to run an LES in a turbine blade passage and I ran into this warning message during my production run:
> 
>                L1/L2 DIV(V)    :   1.9224E-01   2.3951E+00
>                L1/L2 QTL       :   1.9180E-01   2.3014E+00
>                L1/L2 DIV(V)-QTL:   4.3317E-04   6.6792E-01
>                WARNING: DIV(V)-QTL too large!
> 
> I tried to grep it to the source code and found that the quantity QTL refers to the thermal divergence ( I do use usrdiv in my outlet ). But my case is purely from a fluids perspective and does not involve heat transfer. So I am wondering how QTL would pop up in my simulation.  And I also noted that the error message comes up only when I use PN-PN basis function. I would like to know if this error message is a concern at all .
> 
> Regards
> Shriram
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