High temperature problems in cavitation analysis

ecto · October 19, 2012, 10:20

Hi everybody!
I'm using Starccm+ 7.04 to simulate isoctane flowing through a cylindrical pipe in a nozzle of an automotive GDI injector, in particular I have to investigate the occurring cavitation. The pipe is 0.14mm in diameter and 0.3 mm in lenght. Pressure inlet is 120bar.
I set up models with 600'000 and 3'000'000 poly cells, with Standard k-e low y+. In both of them I can see that, as soon as I activate cavitation option, temperatures in the nozzle go crazy, raising the maximum value I set, that's 700K. Pressure, velocity and flow rate are consistent with experimental values.
Maybe someone has had similar experience.
Can someone help me?
Many thanks

ecto · October 19, 2012, 10:22

Ah, I forgot to say that I'm using Eulerian multiphase VOF model.

sieginc. · October 19, 2012, 15:38

I've had a similar thing happen to me, and it looked like that. Unrealistic spikes in strange places as soon as I started the simulation. Initially I used the polyhedral mesher, but then switched to the trimmer and that solved the problem. My guess is that the poly mesher was not able to capture some of the geometry causing my solution to diverge.

ecto · October 19, 2012, 16:03

Thanks for the help, I will try with trim mesh.
Regards

ecto · October 30, 2012, 08:31

I confirm that switching to trim mesh and to k-epsilon two layer all y+ risolved the problem of high T.

October 19, 2012, 10:20	High temperature problems in cavitation analysis	#1
ecto New Member Join Date: Nov 2010 Posts: 23 Rep Power: 16	Hi everybody! I'm using Starccm+ 7.04 to simulate isoctane flowing through a cylindrical pipe in a nozzle of an automotive GDI injector, in particular I have to investigate the occurring cavitation. The pipe is 0.14mm in diameter and 0.3 mm in lenght. Pressure inlet is 120bar. I set up models with 600'000 and 3'000'000 poly cells, with Standard k-e low y+. In both of them I can see that, as soon as I activate cavitation option, temperatures in the nozzle go crazy, raising the maximum value I set, that's 700K. Pressure, velocity and flow rate are consistent with experimental values. Maybe someone has had similar experience. Can someone help me? Many thanks Last edited by ecto; October 19, 2012 at 10:42.

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October 19, 2012, 10:22		#2
ecto New Member Join Date: Nov 2010 Posts: 23 Rep Power: 16	Ah, I forgot to say that I'm using Eulerian multiphase VOF model.

October 19, 2012, 15:38		#3
sieginc. Member adam Join Date: Oct 2011 Posts: 52 Rep Power: 15	I've had a similar thing happen to me, and it looked like that. Unrealistic spikes in strange places as soon as I started the simulation. Initially I used the polyhedral mesher, but then switched to the trimmer and that solved the problem. My guess is that the poly mesher was not able to capture some of the geometry causing my solution to diverge.

October 19, 2012, 16:03		#4
ecto New Member Join Date: Nov 2010 Posts: 23 Rep Power: 16	Thanks for the help, I will try with trim mesh. Regards

October 30, 2012, 08:31		#5
ecto New Member Join Date: Nov 2010 Posts: 23 Rep Power: 16	I confirm that switching to trim mesh and to k-epsilon two layer all y+ risolved the problem of high T.