Hi all, I’m investigating T inventory in a pipe. I originally used a 3D pipe and all was working fine until I played around with surface parameters and it began struggling to converge. I tried adjusting tolerances but it was very finickity so I switched to a 2D pipe slice, with a finer mesh. Obviously my results are now different as it’s finding the inventory in a 2D area.
Before, for the 3D pipe (25mm ID, 35mm OD, L=100mm), I assumed the result was the total number of mols in the volume, so was multiplying the output by 10 to get mols per meter of pipe.
For the 2D simulation, how do I interpret the values I obtain? And how do I normalise to mol per meter of pipe? I took a look here but am still a little confused.
You can see that the 3D simulation is giving me a smaller output for TotalVolume. I assumed this was in the unites mol, so I multiplied by 10 to get mol per meter of pipe (as my mesh was a 3D pipe of 0.1m).
As for the 2D results, I’m not sure what the units are, or how to convert them to mol per meter of pipe.
Hi! So just to clarify: you are running a 2D simulation of a pipe and computing TotalVolume on it.
Is it the radial cross section or an axial cross section? Since you’re asking about “per meter of pipe” I’m assuming it’s an axial cross section like this
If you calculate TotalVolume on this then the units should already be per meter of pipe.
As you rightfully pointed out, TotalVolume integrates \int c dA where c is still in mol/m3 and dA is a surface element in m2. The quantity is therefore in mol/m.
Let me know if there is something I’m not getting.
Thanks for your response - yes, the 2D simulation is an axial slice. So it seems TotalVolume for 2D is mol per meter of pipe, and TotalVolume for 3D is mol in the volume provided (i.e. 0.1m length)?
If this is the case, multiplying my results from the 3D simulation should give the same results as the 2D simulation, however this is currently not the case. I wonder why this is - it could be the difference in mesh? It’s quite a large difference between the two!
