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cfd_multiphyiscs March 9, 2010 12:25

Ansys 11.0 CFX - solving electric potentials and multiphase flow

I am solving a multiphase flow where one fluid is neutral and another fluid is ionized and additionally I am solvig for electric potential in the domain. I am using Electromagnetics Beta feature in Ansys 11.0

However when I activate two fluids under the "Default Domain" tab, I am unable to specify the Electric potential boundary conditions in my domain. The relevant tabs in the Ansys CFX-Pre Gui disappear. I am able to specify the electric fields for a single fluid case.

I am not sure if Electromagentics Beta version is disabled for multiphase flow. Kindly clarify if it is so or if not? Thank you.

Assuming that the electromagentics feature can be used only with single fluid, I need help on how to implement the interaction between the two fluids.
In my simulation, the neutral fluid has influence on the ionized fluid but not vice versa. Hence I have independently solved the flow scenarios for both neutral and ion flow. I now need to couple the neutral flow solution to the ion flow solver so that the solver can calculate the body force source terms due to neutral gas on ion flow.
Kindly let me know if this is possible, if so some direction on how to do it.

Thank you.

ckleanth March 10, 2010 07:16

the emag in cfx 11 is pretty much way in the beta region, gui for emag is not stable and the only way to make sure that you activate emag boundaries is to direly define the boundary conditions using ccl on your def file. this means you need to know exactly what you're doing.

if you manage to make it work for you another issue with cfx11 and emag is with multiphase is that the emag variables are carried by the first defined fluid (i think this is true for all variables in multiphase and then the global variables are renamed as the res file is created, however in the case of emag some variables dont) this means you will have potential however this is the global energy potential in your fluid domain.

furthermore in cfx 11 lorenz forces do affect the momentum equation however joule heating was not included in the energy equation and you need to explicitly add this source term if its important for your solution.

to answer your question, yes it is possible obviously you need to define all emag properties for all phases and quite possibly need ansys support. it is easier to work with cfx 12 as its a properly supported module.

cfd_multiphyiscs March 10, 2010 14:43

Hello ckleanth
Thank you for the reply. As you have indicated working in CFX 12 is more suitable for this problem.

Your quick reply is appreciated

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