# Internal airflow simulation issues

Hi,
I have spent countless hours attempting to run an indoor airflow test to simulate airflow (relatively low volume) for a HRV system and ducting locations.

I cannot seem to get it to run - I face the following issues.

Firstly - snappyhexmesh does not seem to always want to operate correctly (attached file at last attempt would not mesh correctly)

Secondly - when the mesh decides to actually work, sometimes the simulation will fail, it won’t write an openfoam file or something along those lines.

And lastly - when the planets combine and the sim actually runs (currently cannot get this far, without changing parameters the above to issues decided to once again come into play) it seems to only run through one duct outlet instead of the 4 determined, and the extract air ducts seem to not be extracting (at equal pressure in an airtight envelope)

I’ve linked the .3dm and .gh, please any help on this would be greatly appreciated, I’ve lost countless hours over the last month just going round in circles

https://www.dropbox.com/sh/0cn7gxhf8rip1lz/AACy9K1rz4ggu4w_HFg44rRRa?dl=0

The name of geometry should not begin with number. I changed the name to supply_40m3. The mesh can run fine.

Unfortunately, butterfly does not write out the solver’s err file. You can check the error log by opening command prompt and executing the contents of ir.bat file line by line.

Are all the outlets created in the mesh as you have defined them? Have you opened it in Paraview to check? Creating a mesh for your case is time consuming, so the figure is an example.

Thank you minggangyin and kinonotofu,

The mesh now works - but that is as far as it goes. The solver is failing as you can see below. This is the main problem that I have been having (prior to changing the names of the geometry that caused the first issue).

You seem to be failing at parallel run.
Have you checked the error logs for decomposePar and mpirun?
Does the serial run work?

Hi Kino, apologies for the late response.

I have not checked these because I do not know how to. I have moderate abilities in grasshopper, but any deeper than that is outside my knowledge/skill set.

This is how to check the error log.

For example, to check for errors in parallel run, you can type the following into cmd.exe

call "C:\Program Files\blueCFD-Core-2017\setvars.bat"
set PATH=%HOME%\msys64\usr\bin;%PATH%
cd %USERPROFILE%\butterfly\CASENAME
decomposePar  | tee log\decomposePar.log
mpirun -np 4 simpleFoam  -parallel | tee log\mpirun.log
reconstructPar  | tee log\reconstructPar.log
rm -r proc* | tee log\rm.log


CASENAME and 4 (number of cpus) should be changed according to your situation. I think you will get an error with decomposePar or mpirun. Error logs are displayed on the screen.

Have you checked that serial run is OK before parallel run?It’s simple: just disconnect the connection to decompose_par_dict_ in Solution and run the calculation. If you still get the error in the serial run, check the error log again. Now ir.bat file will look like this.

call "C:\Program Files\blueCFD-Core-2017\setvars.bat"
set PATH=%HOME%\msys64\usr\bin;%PATH%
cd %USERPROFILE%\butterfly\CASENAME
simpleFoam | tee log\simpleFoam.log