no vortex shedding - flow over a cylinder

daylen · September 28, 2021, 12:55

Hi, im trying to simulate flow over a cylinder at Re =1.02e4 with simplefoam, komega sst, no vortex shedding appears, i used pimplefoam and its the same, no shedding, why this happens? i should be getting vortex shedding but nothing shows.

marco.müller · September 28, 2021, 13:01

Hi, just looking at your picture I guess your mesh is way too coarse. Also the domain is too small.

daylen · September 28, 2021, 15:34

ok im going to fix that, thanks.

daylen · September 28, 2021, 21:55

i made a finer mesh and got better results, but if i make a more finer mesh simplefoam gives floating point exception, im using gmsh to make the mesh

sqek · September 29, 2021, 09:53

Check your timestep size / CFL number? CFL should normally be below 1 if you want to capture unsteady flows accurately.

dlahaye · September 29, 2021, 13:58

https://wiki.openfoam.com/Vortex_ind...ichael_Alletto

https://wiki.openfoam.com/Vortex_she...el_Guerrero_2D

How to calculate predominant shedding frequency in Strouhal Number

September 28, 2021, 13:01		#2
marco.müller New Member Marco Müller Join Date: Feb 2013 Location: Germany Posts: 23 Rep Power: 13	Hi, just looking at your picture I guess your mesh is way too coarse. Also the domain is too small. daylen likes this.

September 29, 2021, 13:58		#6
dlahaye Senior Member Domenico Lahaye Join Date: Dec 2013 Posts: 730 Blog Entries: 1 Rep Power: 17	https://wiki.openfoam.com/Vortex_ind...ichael_Alletto https://wiki.openfoam.com/Vortex_she...el_Guerrero_2D How to calculate predominant shedding frequency in Strouhal Number daylen likes this.

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September 28, 2021, 15:34		#3
daylen Member Gabriel Join Date: Aug 2021 Posts: 37 Rep Power: 4	ok im going to fix that, thanks.

September 29, 2021, 09:53		#5
sqek Member Join Date: May 2017 Posts: 31 Rep Power: 8	Check your timestep size / CFL number? CFL should normally be below 1 if you want to capture unsteady flows accurately.