I start to do transient calculations with sliding mesh. If the solution seems to be periodic, I write the cas and dat file for each time-step for further postprocessing, but the harddisk-memory you need for this is enormous. Is there a way to reduce this data-volume or is there a way to write out only important data or data that have changed from one timestep to the other ?

John

If you write an interpolation file, the amount of data is much less because only values at the cell centers are included in the file.

In a data file, on the other hand (I am pretty sure), the cell centered values as well as values interpolated to each of the cell faces are stored, along with residuals etc. This makes the data files much larger.

Since you use sliding mesh, you can save a case file at the relevant time step, and write a corresponding interpolation file. When you write the interp file, you will need to specify which solution variables you want (i.e. only velocity, or velocity and pressure etc).

File --> interpolation --> write data.

To view the data that is in the saved interpolation file, you must read in the appropriate case and then

File --> interpolation --> read data

It's my understanding that Fluent created the interpolation capability for continuing a CFD simulation on a separate grid, however it seems to work well for saving the data in a more compact form.