Boiling simulation Outlet Boundary condition isssue

soumitra2102 · February 1, 2019, 20:19

I am simulating a subcooled water pool boiling case under atmospheric pressure, where bulk temperature of the liquid water has reached up to 360K in transient result file.

However, now, maybe due to increased turbulence in the pool, at the free top surface where Pressure Outlet boundary condition is applied, the backflow (of both liquid and vapor phases) is causing solver to stop with fatal overflow error.

How can I correctly model the free surface to let vapor to escape and cause corresponding decrease in the water level?

ghorrocks · February 3, 2019, 04:43

Would a degassing boundary work better than a pressure outlet? But a degassing boundary will not handle volume change very well.

How are you modelling this? Please post your output file and an image of what you are modelling.

regard · April 19, 2019, 15:19

Quote:

Originally Posted by soumitra2102

I am simulating a subcooled water pool boiling case under atmospheric pressure, where bulk temperature of the liquid water has reached up to 360K in transient result file.

However, now, maybe due to increased turbulence in the pool, at the free top surface where Pressure Outlet boundary condition is applied, the backflow (of both liquid and vapor phases) is causing solver to stop with fatal overflow error.

How can I correctly model the free surface to let vapor to escape and cause corresponding decrease in the water level?

hi Soumitra Vadnerkar&Glenn Horrocks
to: Soumitra Vadnerkar
are you use interThermalPhaseFoam for your simulation?
if yes... can you help me for choice the suitable thermal model for subcooled flow boiling ?
if No which solver you used for your simulation

thanks in advance

soumitra2102 · April 19, 2019, 17:33

I am using ANSYS CFX 19.2 for all of my CFD simulation’s Pre-processing, Solving and Post-professing.
RPI wall boiling model along with other necessary closure models have been well implemented in ANSYS CFX.

regard · April 20, 2019, 02:44

thanks for your reply

Goenitz · April 23, 2019, 08:17

Quote:

Originally Posted by soumitra2102

I am using ANSYS CFX 19.2 for all of my CFD simulation’s Pre-processing, Solving and Post-professing.
RPI wall boiling model along with other necessary closure models have been well implemented in ANSYS CFX.

Output file is where your files are saved in project directory
example may be
Project\dp0\CFX\CFX\CFX_001.out

also attach image of file what are you modelling... naming different region in paint will be helpful

February 1, 2019, 20:19	Boiling simulation Outlet Boundary condition isssue	#1
soumitra2102 Member Soumitra Vadnerkar Join Date: Aug 2018 Posts: 70 Rep Power: 8	I am simulating a subcooled water pool boiling case under atmospheric pressure, where bulk temperature of the liquid water has reached up to 360K in transient result file. However, now, maybe due to increased turbulence in the pool, at the free top surface where Pressure Outlet boundary condition is applied, the backflow (of both liquid and vapor phases) is causing solver to stop with fatal overflow error. How can I correctly model the free surface to let vapor to escape and cause corresponding decrease in the water level?

February 3, 2019, 04:43		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,870 Rep Power: 144	Would a degassing boundary work better than a pressure outlet? But a degassing boundary will not handle volume change very well. How are you modelling this? Please post your output file and an image of what you are modelling. __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

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April 19, 2019, 17:33		#4
soumitra2102 Member Soumitra Vadnerkar Join Date: Aug 2018 Posts: 70 Rep Power: 8	I am using ANSYS CFX 19.2 for all of my CFD simulation’s Pre-processing, Solving and Post-professing. RPI wall boiling model along with other necessary closure models have been well implemented in ANSYS CFX.

April 20, 2019, 02:44		#5
regard Member ... Join Date: May 2018 Posts: 37 Rep Power: 8	thanks for your reply