Problem of simulating shape oscillations of Bubble - Multiphase flow

akash · January 25, 2013, 05:45

Hello,
I'm a novice to Fluent. I'm trying to simulate 2D shape oscillations of an air bubble in an incompressible fluid, say water. I had prepared the grid in Pointwise.
I had to define a single domain as I needed to work with structured grid. But when I import the grid in Fluent, the bubble-fluid interface is not detected. Even then I tried using the multiphase option, defined two different fluids. I'm not able to define the phases and appropriate BCs.

How can I explicitly define two different domains in fluent and set the fluid properties respectively. In simple words how will I make Fluent understand which fluid (air and water) is to be used in particular regions.

Also the initial shape of the bubble is complex. It isn't a conic. Please have look at the grid with the attached url. http://imgur.com/0lFY5jD

msaeedsadeghi · January 25, 2013, 23:51

I have done that. As I have understanded, your problem is an enclosure with two phases (air and water). At the initialization you should set the volume fraction of each phase at each cell. It is possible with a UDF. Also you can do it if define a zone in gambit to set it for example as air in fluent.

akash · January 29, 2013, 13:46

Sir,
I want to mesh it as shown in the attached figure in the previous post

. The problem in defining zones in Gambit is that I have to first create two separate faces to define 2 zones. But I don't want to separately mesh the interior region. I tried to split the mesh along the nodes on the on the interface, but I got some error messages.
Basically what I want is when I import the grid in Fluent, it should identify two different regions and also identify the interface boundary between them.
Please let me know on how can I split the mesh along a given edge in gambit and define it as an interface.

January 25, 2013, 05:45	Problem of simulating shape oscillations of Bubble - Multiphase flow	#1
akash New Member Akash Join Date: Jan 2013 Location: India Posts: 20 Rep Power: 13	Hello, I'm a novice to Fluent. I'm trying to simulate 2D shape oscillations of an air bubble in an incompressible fluid, say water. I had prepared the grid in Pointwise. I had to define a single domain as I needed to work with structured grid. But when I import the grid in Fluent, the bubble-fluid interface is not detected. Even then I tried using the multiphase option, defined two different fluids. I'm not able to define the phases and appropriate BCs. How can I explicitly define two different domains in fluent and set the fluid properties respectively. In simple words how will I make Fluent understand which fluid (air and water) is to be used in particular regions. Also the initial shape of the bubble is complex. It isn't a conic. Please have look at the grid with the attached url. http://imgur.com/0lFY5jD Last edited by akash; January 25, 2013 at 05:47. Reason: url attached wasn't shown

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January 25, 2013, 23:51		#2
msaeedsadeghi Senior Member SSL Join Date: Oct 2012 Posts: 226 Rep Power: 14	I have done that. As I have understanded, your problem is an enclosure with two phases (air and water). At the initialization you should set the volume fraction of each phase at each cell. It is possible with a UDF. Also you can do it if define a zone in gambit to set it for example as air in fluent.

January 29, 2013, 13:46		#3
akash New Member Akash Join Date: Jan 2013 Location: India Posts: 20 Rep Power: 13	Sir, I want to mesh it as shown in the attached figure in the previous post . The problem in defining zones in Gambit is that I have to first create two separate faces to define 2 zones. But I don't want to separately mesh the interior region. I tried to split the mesh along the nodes on the on the interface, but I got some error messages. Basically what I want is when I import the grid in Fluent, it should identify two different regions and also identify the interface boundary between them. Please let me know on how can I split the mesh along a given edge in gambit and define it as an interface.