Initial conditions for granular phase in Eulerian multiphase flow

    • Bharath_Vittal
      Hi I am using Eulerian Multiphase physics to model multiphase counter flow in blast furnace. I am trying to run a steady state case in which a solid granular phase enters the domain from the top and exits the domain at the bottom. The gas phase enters the domain from the bottom and exits at the top. The detailed geometry cannot be specified here because of confidential reasons. All the material properties are obtained from literature.
      Boundary conditions: For simplicity reason, the gas inlet velocity is set as 0 and a mass flow rate is specified at the top for the solid phase. Volume fraction for solid solid phase is specified both at inlet and outlet. Top pressure is atmospheric.
      My question is regarding the initial conditions:
      I am using standard initialization to specify only the velocity and volume fraction for solid granular phase. The velocity is calculated from the inlet mass flow rate. Any value of solid phase volume fraction above 0 throws a floating point error, whereas a with a zero solid volume fraction, the simulation runs, but does not converge. Could anyone throw some light into the reasons behind floating point error for any solid volume fraction above 0? Moreover, what are the guidelines to initialize in such case, without being far away from the steady state solution?
    • Prashanth
      Ansys Employee

      Hey Bharath. I don't think using volume fraction values other than 0 or 1 is a good idea. I would suggest to use a VF value of 1 at the solid phase inlet boundary. Don't worry if solution doesn't converge.

      Also, a good approach is to run a transient study of the same if it is difficult to converge using steady state case.

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