CFD Simulation of Flow Through a Pipe in an Air Domain

hsm825hsm825 Member


I want to simulate a pipe (with an inlet and outlet) inside a large air domain. In addition, I want the pipe walls to provide heat to the flow inside the pipe. So the flow at the outlet is at a higher temperature than the flow at the inlet. I then want to see how the hot flow at the outlet interacts with the air domain. 

When I set this up, I am unable to obtain an "Inlet" for the pipe inside the air domain. Could you please advise? The air domain is supposed to be stagnant, and then the pipe inlet sucks in air at a velocity that I want to specify. The air then goes through the pipe, becomes warm, and I want to see how the warmer air interacts with the air domain surrounding the outlet. How do I go about setting this up so that I can successfully obtain a pipe inlet boundary condition inside Fluent?


  • KremellaKremella Admin
    edited April 30


    Please share some screenshots of the geometry so we can understand your problem better. Is the same air domain connecting both inlet and outlet?


  • JuliaCarinaJuliaCarina Member
    edited May 13


    I am doing almost exactly the same, but I want to add an exhaust fan at the outlet . I would like to define the stagnant air domain inside the pipe, and then set the nitrogen mass flow at the inlet in order to find out the mass flow at the outlet, which is gonna be nitrogen plus air. The nitrogen flow is at 235K and the pipe surface is at 325K. The duct is retangular, the outlet is on the upper surface of the duct, while the inlet is on the lower side, both of tem are circular shaped. The problem is: once I set the air domain inside the duct, I am not able to set a nitrogen mass flow at the inlet.I tried to create a mixture template, with nitrogen and air, but I don't know the mass fraction of each one.

    I would appreciate some help!


  • KremellaKremella Admin
    edited May 18

    Hello Julia,

    If you use a Multiphase model, you should be able to define your primary and secondary phases. Once you do that, you can specify the flow rate and volume fraction of your secondary phase at the inlet. So, if Nitrogen is your secondary phase, you should be able to specify the volume fraction = 1 at the inlet boundary. This will ensure that Nitrogen enters your computational domain. 

    Hope this helps.


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