[DaltonStone]

Is it possible to draw a continuous line as in the figure in Fluent and export the data only on that line?

For example, I have a mass fraction and, therefore, a change along the way, I need to trace that change, but I cannot export this result.

[LuckyTran]

Create the line using the create surface tool. You can create a line by declaring end-point to end-point. Do this for each segment and then merge all the lines together into one line. Or you can leave them as separate lines.

Then go to file write solution data and choose the line or all the lines and choose mass fraction as the export variable under quantities. The lines will be listed as surfaces because Fluent categorically treats them as surfaces.