Model developed through stl file

Palabos General
#1

Hi all,
I build a model through a stl file, but the simulation results are out of my expect and the average energy shown in terminal is nan or -nan. I just wonder what it means. Does that mean the calculation can not converge? how can I adjust the simu parameters?
The xml file reads as follows:

<?xml version="1.0" ?> ./channel.stl 0.0005 0.012 
<!-- The STL geometry provided by the user has openings (inlets and outlets).
     It must not be provided by the user closed. -->
<openings>
    <!-- 0 means x-direction, 1 means y-direction and 2 means z-direction. -->
    <sortDirection> 0 </sortDirection>
    <!-- According to the sortDirection, the user provides which openings are
         inlets and which are outlets. -->
    <type> Inlet Outlet </type>
</openings>
3.7037e-06 1080 3.0-9 0 800 0.00062 1000 0 1.e-1 
<performOutput>      True   </performOutput>
<doImages>           True   </doImages>
<!-- Extrapolation scheme for the off lattice boundary condition. -->
<useAllDirections>   True   </useAllDirections>
<!-- Use an off lattice boundary condition which is closer in spirit to
     regularized boundary conditions. -->
<useRegularizedWall> True   </useRegularizedWall>
<!-- Use an incompressible BGK model or the standard BGK model. -->
<useIncompressible>  True   </useIncompressible>
<!-- Use Poiseuille profile as an inflow boundary condition, or use
     a simple plug profile instead. -->
<poiseuilleInlet>    True   </poiseuilleInlet>
<convectiveScaling>  False  </convectiveScaling>

Regards,
Si

#2

Hi Si,
I’m not an expert on Palabos, but I faced the same issue some weeks ago. Do you obtain nan values in other physical quantities, such as density, velocity, etc.? Otherwise, the problem might be constrained to the lines where you compute the average energy. Does it start at the beginning of the simulation or it appears after some time?

According with the xml file you provided, I think that you are based on the aneurysm example. Are you using a provided example (like aneurysm.cpp) and just changing the stl file, or are you using your own palabos implementation?

In my case, the problem was that I wasn’t setting the inlets and outlets properly. I figured it out by plotting the profiles at these boundaries in the first iteration. I solved it by following the aneurysm example. Let me know if that’s your case so I can try to help you.

Regards,
Emilio