Hi,

I'm working on Large eddy simulation with ANSYS Fluent. I have been using "data sampling" to obtain the time statistics, but I found it gave me very strange results.

The testing case shown below is a constant pressure driven channel flow at friction Reynolds number 2000. The two simulations were initialized with the same velocity field. As shown in the journal files below, I collected the instantaneous velocities and computed the statistics myself in the first simulation. In the second simulation, I activated the "data sampling" option. The data sampling frequencies were set the same for the both cases, but the results are quite different.

The results computed from instantaneous snapshots look more reasonable to us since we are able to close the momentum budget with the resolved shear stress but not the one solved by ANSYS Fluent.

**Journal for the first simulation:**

/file/set-tui-version "19.3"

/file/read-case-data "start"

solve/dual-time-iterate 2500

file/write-case-data 01_inst

solve/dual-time-iterate 2500

file/write-case-data 02_inst

solve/dual-time-iterate 2500

file/write-case-data 03_inst

solve/dual-time-iterate 2500

file/write-case-data 04_inst

solve/dual-time-iterate 2500

file/write-case-data 05_inst

solve/dual-time-iterate 2500

file/write-case-data 06_inst

solve/dual-time-iterate 2500

file/write-case-data 07_inst

solve/dual-time-iterate 2500

file/write-case-data 08_inst

solve/dual-time-iterate 2500

file/write-case-data 09_inst

solve/dual-time-iterate 2500

file/write-case-data 10_inst

solve/dual-time-iterate 2500

file/write-case-data 11_inst

solve/dual-time-iterate 2500

file/write-case-data 12_inst

solve/dual-time-iterate 2500

file/write-case-data 13_inst

solve/dual-time-iterate 2500

file/write-case-data 14_inst

solve/dual-time-iterate 2500

file/write-case-data 15_inst

solve/dual-time-iterate 2500

file/write-case-data 16_inst

solve/dual-time-iterate 2500

file/write-case-data 17_inst

solve/dual-time-iterate 2500

file/write-case-data 18_inst

solve/dual-time-iterate 2500

file/write-case-data 19_inst

solve/dual-time-iterate 2500

file/write-case-data 20_inst

exit yes

**Journal for the second simulation:**

/file/read-case-data "start"

solve/initialize/init-flow-statistics

/solve/set/data-sampling yes 2500 yes yes

solve/dual-time-iterate 50000

file/write-case-data final

exit yes

Best,

Weiyi