Isolating a model area?

James88 · March 7, 2012, 18:10

Hey everyone,

I am not sure how to explain what I need... Basically, I am trying to measure the vortex shedding frequency given from finite cylinders at varying length/diameter ratios. I understand from previous research that the Strouhal number varys along the length of the cylinder.
In my 2D simulations, I obtained the frequency by creating a lift coefficient report, and inverting the time period, which ended up giving me the expected value.
However, I would like to measure the shedding frequency for different areas of the cylinder... say, the centre, and halfway from the centre to the finite end.
I am unsure how to go about this. My first though would be to use a function (IF IT EXISTS!) that isolates an area of the cylinder, so that could be the part selected for my lift report... Does anything like this exist?

If any of you know any other ways to go about this, I would value your input!
Also, I saw that there is a Strouhal number Fourier transform function in the data set tools. How would I go about using this?

Many thanks to you all!

James

abdul099 · March 12, 2012, 03:17

Just split up the boundary. I would create a block to split and do an intersect in surface repair, and afterwards a split by feature curve. You will get different boundaries which you can choose separately for your reports.
You need to remesh after the split, since you need a well defined border between your different boundaries. That's why I would do it on the parts level.

March 7, 2012, 18:10	Isolating a model area?	#1
James88 New Member James Join Date: Feb 2012 Posts: 11 Rep Power: 14	Hey everyone, I am not sure how to explain what I need... Basically, I am trying to measure the vortex shedding frequency given from finite cylinders at varying length/diameter ratios. I understand from previous research that the Strouhal number varys along the length of the cylinder. In my 2D simulations, I obtained the frequency by creating a lift coefficient report, and inverting the time period, which ended up giving me the expected value. However, I would like to measure the shedding frequency for different areas of the cylinder... say, the centre, and halfway from the centre to the finite end. I am unsure how to go about this. My first though would be to use a function (IF IT EXISTS!) that isolates an area of the cylinder, so that could be the part selected for my lift report... Does anything like this exist? If any of you know any other ways to go about this, I would value your input! Also, I saw that there is a Strouhal number Fourier transform function in the data set tools. How would I go about using this? Many thanks to you all! James

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Superlinear speedup in OpenFOAM 13	msrinath80	OpenFOAM Running, Solving & CFD	18	March 3, 2015 05:36
New implemented algebraic Reynolds stress model	volker	OpenFOAM	13	October 21, 2013 00:01
LES and combustion model	Margherita Cadorin	CFX	0	October 29, 2008 05:24
simulation results for k-w model and SST model	Li	CFX	7	June 29, 2007 04:19
Advanced Turbulence Modeling in Fluent, Realizable k-epsilon Model	Jonas Larsson	FLUENT	5	March 13, 2000 03:27

March 12, 2012, 03:17		#2
abdul099 Senior Member Join Date: Oct 2009 Location: Germany Posts: 636 Rep Power: 21	Just split up the boundary. I would create a block to split and do an intersect in surface repair, and afterwards a split by feature curve. You will get different boundaries which you can choose separately for your reports. You need to remesh after the split, since you need a well defined border between your different boundaries. That's why I would do it on the parts level.