Problems in water-air flow simulation

bybygary · April 29, 2014, 11:19

Hi,
I am trying to simulate the two-phase flow in Ansys Fluent. But the error message always shows up when I try to run the calculation. The error message is
'# Divergence detected in AMG solver: mp-x-momentum -> Decreasing coarsening group size!
# Divergence detected in AMG solver: mp-x-momentum -> Increasing relaxation sweeps!
# Divergence detected in AMG solver: pressure correction -> Turning off correction scaling!
# Divergence detected in AMG solver: pressure correction -> Increasing relaxation sweeps!

Error: Divergence detected in AMG solver: pressure correction
Error Object: #f'

The model in my simulation is a simple one. The flow area is 2D, axis-symmetric and rectangular. The air and water come in from the top and come out from the bottom. Eulerian model and k-e model is applied in my simulation. Could anyone give me some suggestion? Thanks in advance!

bybygary · April 29, 2014, 16:06

Hi, I have changed the geometry into full region instead of axis-symmetric and the error message never shows up again. I am so confused since I used the same parameters!! Could anyone explain this?

bybygary · April 29, 2014, 16:12

And I also find something weird. In the axis-symmetric model, when I choose compute from outlet in the solution initialization, the value of gauge pressure is '-1.#IND'. Is this the reason for the problem? I don't know why since I have set the boundary condition for the outlet (it is pressure-outlet).

April 29, 2014, 11:19	Problems in water-air flow simulation	#1
bybygary New Member Ye Bai Join Date: Mar 2014 Posts: 9 Rep Power: 12	Hi, I am trying to simulate the two-phase flow in Ansys Fluent. But the error message always shows up when I try to run the calculation. The error message is '# Divergence detected in AMG solver: mp-x-momentum -> Decreasing coarsening group size! # Divergence detected in AMG solver: mp-x-momentum -> Increasing relaxation sweeps! # Divergence detected in AMG solver: pressure correction -> Turning off correction scaling! # Divergence detected in AMG solver: pressure correction -> Increasing relaxation sweeps! Error: Divergence detected in AMG solver: pressure correction Error Object: #f' The model in my simulation is a simple one. The flow area is 2D, axis-symmetric and rectangular. The air and water come in from the top and come out from the bottom. Eulerian model and k-e model is applied in my simulation. Could anyone give me some suggestion? Thanks in advance!

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April 29, 2014, 16:06		#2
bybygary New Member Ye Bai Join Date: Mar 2014 Posts: 9 Rep Power: 12	Hi, I have changed the geometry into full region instead of axis-symmetric and the error message never shows up again. I am so confused since I used the same parameters!! Could anyone explain this?

April 29, 2014, 16:12		#3
bybygary New Member Ye Bai Join Date: Mar 2014 Posts: 9 Rep Power: 12	And I also find something weird. In the axis-symmetric model, when I choose compute from outlet in the solution initialization, the value of gauge pressure is '-1.#IND'. Is this the reason for the problem? I don't know why since I have set the boundary condition for the outlet (it is pressure-outlet).