Output transient body forces in text file during analysis

karachun · February 27, 2019, 04:20

Hi guys!

I model laminar (Re~100) vortex shedding of circular cylinder using CFX in pseudo 2D. I perform transient calculation One of the main goals is to compare Strouhal number with theoretical values. To do so I have to output time history of lift force and calculate period it oscillation.

One varialt of solving this problem is to save full transient results (not all, but rather each 5 or 10 to get reasonable chart resolution and size of result files) and postprocess them in CFD-Post. However, this is disk space consuming way and creation of one chart in CFD-Post can take 5-10 minutes long.

So my question: Is it possible to save body force results during calculation in separate text file (I monitor body forces during calculation using expression so this calculation "on fly" is possible but I don’t know how to extract this data) without saving thousands of transient result files?

Thanks in advance.

urosgrivc · February 27, 2019, 05:15

You could make a Monitor point, and set it in output controls to be plotted while the solver is running.
then Export the values from the solver monitor of only force for all timesteps

karachun · February 27, 2019, 05:31

Thanks, the solution was very simple, just press RMB on monitor screen

February 27, 2019, 04:20	Output transient body forces in text file during analysis	#1
karachun Senior Member Join Date: Nov 2015 Posts: 246 Rep Power: 12	Hi guys! I model laminar (Re~100) vortex shedding of circular cylinder using CFX in pseudo 2D. I perform transient calculation One of the main goals is to compare Strouhal number with theoretical values. To do so I have to output time history of lift force and calculate period it oscillation. One varialt of solving this problem is to save full transient results (not all, but rather each 5 or 10 to get reasonable chart resolution and size of result files) and postprocess them in CFD-Post. However, this is disk space consuming way and creation of one chart in CFD-Post can take 5-10 minutes long. So my question: Is it possible to save body force results during calculation in separate text file (I monitor body forces during calculation using expression so this calculation "on fly" is possible but I don’t know how to extract this data) without saving thousands of transient result files? Thanks in advance.

February 27, 2019, 05:15		#2
urosgrivc Senior Member urosgrivc Join Date: Dec 2015 Location: Slovenija Posts: 365 Rep Power: 12	You could make a Monitor point, and set it in output controls to be plotted while the solver is running. then Export the values from the solver monitor of only force for all timesteps karachun likes this.

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February 27, 2019, 05:31		#3
karachun Senior Member Join Date: Nov 2015 Posts: 246 Rep Power: 12	Thanks, the solution was very simple, just press RMB on monitor screen