chamber simulation problem

hamedhamed · June 25, 2013, 08:01

Hi everybody,

Im simulating the air flow into a chamber. the dynamic mesh was generated by using ESE chamber modeler in AVL Fire v2011. each time I want to start the simulation from the beginning (370 CA), around 435 CA I have a lot of problems with run. in fact turbulent energy and dissipation rate residuals do not behave well and have a oscillating shape. is there anyway to get rid of it?

regards,

hamed

kimmhw · June 26, 2013, 22:00

Hi hamed,

Frankly, your explanation is too vague.
I guess your problem happens during intake stroke.

In this kind of case, the problem may be very specific to your model.

But in general, I can say you should check the followings.
- check the mesh quality for whole dynamic mesh
==> you can use the cell quality check during dummy run
- boundary condition
==> inlet/outlet condition
- timestep (delta CA and engine speed)
- min. and max. iterations
- relaxation factors

hamedhamed · June 29, 2013, 07:48

Hi,

Thanks for response
I lowered the underrelaxtion factor of turbulent dissipation rate and the simulation resumed.

regards,

Hamed

June 25, 2013, 08:01	chamber simulation problem	#1
hamedhamed New Member hamed Join Date: Feb 2013 Posts: 24 Rep Power: 12	Hi everybody, Im simulating the air flow into a chamber. the dynamic mesh was generated by using ESE chamber modeler in AVL Fire v2011. each time I want to start the simulation from the beginning (370 CA), around 435 CA I have a lot of problems with run. in fact turbulent energy and dissipation rate residuals do not behave well and have a oscillating shape. is there anyway to get rid of it? regards, hamed

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June 26, 2013, 22:00		#2
kimmhw New Member Myunghwan Kim Join Date: Jul 2012 Posts: 29 Rep Power: 12	Hi hamed, Frankly, your explanation is too vague. I guess your problem happens during intake stroke. In this kind of case, the problem may be very specific to your model. But in general, I can say you should check the followings. - check the mesh quality for whole dynamic mesh ==> you can use the cell quality check during dummy run - boundary condition ==> inlet/outlet condition - timestep (delta CA and engine speed) - min. and max. iterations - relaxation factors

June 29, 2013, 07:48		#3
hamedhamed New Member hamed Join Date: Feb 2013 Posts: 24 Rep Power: 12	Hi, Thanks for response I lowered the underrelaxtion factor of turbulent dissipation rate and the simulation resumed. regards, Hamed