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

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

You may want to use lx1=10 and compile Nek with K10_MXM in case your running on machine with AMD 10h processors. In addition you can lower the pressure tolerance to 5e-5 to save computational time. Is there a specific reason not to use the PN/PN-2 formulation? Your pressure iterations are quite high but I guess this is because of your mesh. At the moment the PN/PN does not support our multi-grid preconditioner and you're more sensitive to high aspect ratios (effected by the element size + N). Also please I recommned to use  dt = -3e-3 and param(27)=2. Typically a Courant number of two gives you the best performance for the characteristics scheme.

I may help to visualize the difference in divergence. Where are the high values (at element boundaries, domain boundaries, etc.)? In your case QTL contains the user specified divergence at the outflow.

Stefan

 



On May 3, 2010, at 10:52 PM, nek5000-users at lists.mcs.anl.gov wrote:

> Hi Stefan,
> 
> I am running an LES with the following parameters:
> 
> 1. p101=3 and p103 =0.05(filter weight).
> 2. De aliasing enabled and set to 16. (lxd = 16 )
> 4. lx1 = 11
> 3. Yes, IFCHAR is on and a CFL close to 2 is used.
> 4. I add some divergence to the flow outlet using the same procedure detailed in the examples.
> 
> This is my first flow through the domain and I intend to run it for a couple more depending on the results.
> 
> Thank you for the info on order of interpolation polynomial. I would have to refine my domain in order to match the resolution by reducing the lx1. I will look into it.
> 
> Please find attached pieces of rea and log file stacked together in the attachment. Thanks.
> 
> Regards
> Shriram
> 
> 
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