Thrust of a pipe flow

Easyqus · January 18, 2016, 11:50

Hi

I have an unsteady pipe flow (sinusoidal velocity profile) which outputs into a large domain. The geometry is specified as 'axisymmetric'.

I want to measure the thrust of the jet a short distance downstream of the pipe exit, how can I do this?

I know I can monitor the pressure, velocity and density at a range of monitor points and then put them in a momentum balance equation etc. but the only way I know how to do that is setting up parameter points at each monitor point individually. Say I had 20 monitor points, that would create 60 output files to then process which isn't ideal. I have tried using a 'rake' but am unsure what data that is outputting as it only outputs one value for the whole 'rake'. Would I use integral, mass-averaged, area-averaged?!?! And how would I then calculate the force for fully revolved pipe?

I know there must be a quick and easy way to do this and I have tried looking but it either outputs 'zero' or I'm not certain what it's outputting (and hence how to interpret the value!)

Any help would be hugely appreciated, thank you.

LuckyTran · January 20, 2016, 02:32

You could create a function, either a custom field function or a UDF for the stream thrust and then you could integrate this stream thrust.

January 18, 2016, 11:50	Thrust of a pipe flow	#1
Easyqus New Member a m s Join Date: Dec 2015 Posts: 5 Rep Power: 10	Hi I have an unsteady pipe flow (sinusoidal velocity profile) which outputs into a large domain. The geometry is specified as 'axisymmetric'. I want to measure the thrust of the jet a short distance downstream of the pipe exit, how can I do this? I know I can monitor the pressure, velocity and density at a range of monitor points and then put them in a momentum balance equation etc. but the only way I know how to do that is setting up parameter points at each monitor point individually. Say I had 20 monitor points, that would create 60 output files to then process which isn't ideal. I have tried using a 'rake' but am unsure what data that is outputting as it only outputs one value for the whole 'rake'. Would I use integral, mass-averaged, area-averaged?!?! And how would I then calculate the force for fully revolved pipe? I know there must be a quick and easy way to do this and I have tried looking but it either outputs 'zero' or I'm not certain what it's outputting (and hence how to interpret the value!) Any help would be hugely appreciated, thank you.

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January 20, 2016, 02:32		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,674 Rep Power: 66	You could create a function, either a custom field function or a UDF for the stream thrust and then you could integrate this stream thrust.