[-Maxim-]

Ronald, I would ask in the Fluent forum...

[vishu343]

Originally Posted by Fernando R.

I was testing the results with this method and noticed that the value of torque obtained with the monitor point differed a bit from the value acquired by using the 'Function Calculator' (in Calculators) in a given timestep.

So, to have an idea of this difference I've made a simple simulation of a rotating "square" in an air flux, first with it still, to have the inicial values, and then with it moving, and a monitor point measuring the force in the x direction in the sides of the square (defined as "paredes").

After, I've compared the data exported from the monitor point and the force in the x direction evaluated at each timestep using the 'Function Calculator'. The data is shown in the third image (in the table, data refers to "exported data", and manual to data obtained with the function calculator).

It seems that the x axis using the monitor point is refers to a frame of reference fixed in the rotating domain. I've tried marking the "Coord Frame" box and selectinig the "Coord 0" (the only one that appear), but the result is the same.

How can I export the data referred to the global coordinate system?

Hi,

I am facing same problem now. I do not know but you might have looked up in help file with "Force" as a topic. There they have defined why this difference is there but I am not sure about how to solve this problem.

If you know any means then kindly let me know. This problem is specifically for rotating transient cases.

[gbrajtm]

Originally Posted by mvoss

in case you did not set the monitor point before calculating, here is a little script which loops through each time step for a given res-file. start it from the cfx command line via cfx5perl. res-file needs to be next to the script (or viceversa).

>load filename=YOURRESFILE.res
! 	$Liste = getValue("DATA READER","Timestep List");
!	@TIMELIST = split(/,/,$Liste);
!	print "@TIMELIST \n";
!	open OUT, ">YOURDATA.dat";
!	print OUT "Time;Massflow Inlet;Massflow Düse;Massflow Mündung\n"; #HEADER
!	foreach $TS(@TIMELIST){
> 		load timestep = $TS
! 		print "calculating timestep $TS \n";
!		($time, $timeunits) = evaluate("Time");
! 		$pin=massFlow("INLET");
! 		$pduese=massFlow("Domain Interface 1 Side 2");
! 		$pmuendung=massFlow("Domain Interface 2 Side 1");
!		print 		"$time;$pin;$pduese;$pmuendung \n";
!		print OUT 	"$time;$pin;$pduese;$pmuendung\n";
!	};
!		close OUT;
> close

Hi,

I wanted an expression for calculating the force at a region for particular time step using CEL. The present expression I am using is (force_x()@piston), I have to select the time step to select each time to calculate the force for the particular time step. If I could manage to modify the present expression to calculate through expression.
Please help.

[lowdo]

Originally Posted by Fernando R.

I was testing the results with this method and noticed that the value of torque obtained with the monitor point differed a bit from the value acquired by using the 'Function Calculator' (in Calculators) in a given timestep.

So, to have an idea of this difference I've made a simple simulation of a rotating "square" in an air flux, first with it still, to have the inicial values, and then with it moving, and a monitor point measuring the force in the x direction in the sides of the square (defined as "paredes").

After, I've compared the data exported from the monitor point and the force in the x direction evaluated at each timestep using the 'Function Calculator'. The data is shown in the third image (in the table, data refers to "exported data", and manual to data obtained with the function calculator).

It seems that the x axis using the monitor point is refers to a frame of reference fixed in the rotating domain. I've tried marking the "Coord Frame" box and selectinig the "Coord 0" (the only one that appear), but the result is the same.

How can I export the data referred to the global coordinate system?

Fernando, did you ever find a resolution to this issue? I'm finding the same thing (with both torques and forces reported on a part in a rotating domain), which seems to me to be contrary to what would be expected from reading the user manual.