[glypo]

I've run a handful of different external aero cases. I am very surprised to see meshing and solution running significantly faster when output is set at binary compared to ASCII. The only difference in these cases is the setting of 'writeFormat' in the controlDict. Time stated below is User time. Please note each case is an entirely different geometry, block mesh & type).

Case1 - snappyHexMesh - 4.4 million cell
Binary: 1 hr 24 min
ASCII: 3 hr 0 min
Percentage decrease: 53%

Case2 - snappyHexMesh - 1.5 million cell
Binary: 20 min
ASCII: 23 min
Percentage decrease: 10%

Case2 - simpleFoam - 1700 steps
Binary: 9 hr 04 min
ASCII: 11 hr 52 min
Percentage decrease: 24%

Case3 - snappyHexMesh - 4.1 million cells
Binary: 9 hr 18 min
ASCII: 10 hr 15 min
Percentage decrease: 10%

I appreciate that writing ASCII might slow the system, perhaps a minute or so over a long run, but nothing like the significant and repeatable amounts I've encountered. Surely OpenFOAM can only 'understand' binary, thus even when running 'ASCII' these files are read into the system memory as binary? There shouldn't be any major performance difference, but there is. Has anybody else experienced this? Any explanations or solutions other than running foamConvertMesh before and after each run would be greatly appreciated.