Fluids

Fluids

How to establish the proper temperature gradient in a CHT case with phase change?

    • acukrov
      Subscriber

      Hi,

      with this message I would like to ask a question related to application of two-equation turbulence model in a simulation of multiphase flow with phase change using multi-fluid VOF model available in Ansys Fluent.

      The problem is stagnation of temperature field at the simulation start, shown in the attached figure, although the solid material is silver. The high temperature solid (873,15 K) is subjected to a vapor-liquid system, and the result is compared to data extracted from film boiling study [1] using [2]. The "Coupled" boundary condition is applied under thermal tab at the interface wall.

      The "dispersed "formulation of Realizable k-epsilon turbulence model has been used; with vapor as the dispersed phase (occupies the wall adjacent cells; zero velocity magnitude), and liquid as the continuous phase.

      The question is: "How one may enhance the transient heat transfer from solid to quiescent vapor phase by application of turbulence model, to ensure more realistic distribution of the temperature field at the simulation start?"

      Many thanks in advance!

      Kind regards,

      Alen

    • Rob
      Ansys Employee
      What initial conditions did you use compared to the experiment?
    • acukrov
      Subscriber
      Dear Rob the solid is initially at 873,15 K. First wall adjacent cell is filled with vapor (superheated), while the remainder of the fluid domain is filled with saturated water.
      The initial temperature in vapor cell follows the logarithmic law, since the domain is axisymmetric. Velocity fields of both the phases are initially set to zero.
      Kind regards Alen

    • Rob
      Ansys Employee
      How do you set that in the experiment?
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