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Change mass or molar fraction of a mixture

    • Pete
      Subscriber

      Hello All,

      I am looking to modify the content of H2O in an air and H2O vapour mixture. This mixture is set as the internal fluid in the domain, and is used to set the humidity of the environment in which the simulation takes place. I am revisiting this simulation which I ran several years ago and forgot how to change it. Thank you in advance for any help and if more info is needed please let me know. See attached image below.

        Screenshot showing setup tree in Fluent, including the mixture under materials, the fluid under cell zone conditions, and intenal boundary in which it used for

    • Rob
      Forum Moderator

      The mixture is where Fluent holds the materials that are in the domain, with one mixture per phase where applicable. The amount of species in the domain is set via boundary conditions and source terms. 

      Ignore the "internal" boundary, the mixture is attached to the cell zone. 

      • Pete
        Subscriber

        Hi Rob, thank you for your reply. From what I remember about this simulation, the air within the domain had a specified air/H2O mixture and the air entering through the inlet also had a specified air/H2O mixture. I have found how to modify the inlet air/H2O mixture (in inlet boundary conditions), but how would I modify the air/H2O mixture of the domain. Is it by going into the internal boundary condition? I could not find anything. Any assistance on this is greatly appreciated. Thanks.

    • Rob
      Forum Moderator

      Patch, assuming it's either constant (no boundaries) or changes based on the boundary flow (flow boundaries). It's on the panel with the initialisation options. 

      • Pete
        Subscriber

        I see it. Is this molar or mass fraction? I assume this is also where I would set the ambient temperature of the domain? Thanks.

    • Rob
      Forum Moderator

      Initial value, yes. The wall/flow boundaries are where you'd set their temperature. Remember, initialisation and patch are the "iteration 0" result, the solver will then work towards the solution based on the boundary and cell conditions (cell - source terms, porous media etc). 

      It'll say on the panel, probably mass fraction. 

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