Basic Question about Time Directories Created
 

I am running v2006. I ran a very basic pipe flow simulation for a certain number of time steps (setting a Co max and using adjustTimeStep). I also set an initial deltaT. Everything runs fine. All of the solution time step directories I requested are present, but there is an additional one present. A time directory is created that is named "5e-05", the value I used for deltaT. This time directory only contains "U" and "p" files, and a "polyMesh" subdirectory.

Why is this directory written?

At the end of the simulation I realized I wanted to go back and restart the sim halfway through, seeding the flow with massless Lagrangian particles. Again, everything worked fine and all time directories output after my restart contain Lagrangian particle data. Once again, though, I have an additional output time directory this one is called "4.02742e-05", and contains "U" and "p" files, and a "polyMesh" subdirectory as well. This value doesn't correspond to the deltaT in my controlDict, nor does it correspond to the deltaT at my restart time step (my time step is always changing because it is controlled via Courant number).

These new directories I don't remember asking for actually appear any time I attempt another restart of the sim. It seems OpenFoam is re-writing out the mesh every time I attempt a restart, but nothing about the mesh is changing. I'm not imposing any mesh motion or adaptation. Is there someway to tell OpenFoam to instead use the mesh in constant/polyMesh?

WAIT!!!!!!

I'm running a script to kick off my simulation and it includes a decomposePar command. I believe these directories are the parallelized mesh.

That makes a lot more sense!