Fluids

Fluids

reversed flow at mass flow inlet species transport

    • imungan
      Subscriber

      Hello. I am simulating ethylene fueled combustion case. I did aerodynamics analysis. In second analysis fuel injected into domain. While running i am facing reversed flow and temperature problem. However it did not crash. When iterations are finished, i navigate the result. The residual is not reasonable. What should i do? Thnak you in advanced.

      You can see the screenshot of required info below. 

       

    • DrAmine
      Ansys Employee

      Well the global scaled residuals you are sharing are telling me that the case did not converge and the results should not be trusted.

      Are the inputs into you p-farfield correct? Where is it located?

    • imungan
      Subscriber

       

      I dont think inputs are incorrect. They are corresponding to Total pressure 164,5 kPa and total temp 2204 K with Mach 4,5

       

    • DrAmine
      Ansys Employee

      I did not wrote they are incorrect: I wrote please check (espcially if the proper isentropic exponent is used there).

      Are you using the pressure based solver?

    • imungan
      Subscriber

      density based solver

    • DrAmine
      Ansys Employee

      Makes sense. Can you list the model settings you are using. Thanks.

    • imungan
      Subscriber

      Operating Pressure = 0

      Density Based Solver

      k-w sst - compressibility effect

      species transport - volumetric - finite rate / no tci - thermal diffusion - ethylene/air

      ethylene/air --> density: ideal gas - viscosity: ideal gas mixing law - mass diffusivity: kinetic theory - thermal diffusion: kinetic theory

      air ---> density: ideal gas - viscosity: sutherland

      inlet (pressure far field) --> P=5568,4 Pa - 4,5 Mach -T=436,4 K - Intensity and hydraulic = 5/0,0441 m - O2:0,232 h20:0,032

      fuel (mass flow inlet) --> 5,8e-4 kg/s - 100666,8 Pa - total temp:300 K - intensity - hydraulic = 5/7,5e-4 m - c2h4=1 

      outlet --> intensity and hydraulic = 5 / 0,0675 m (rest is default)

      hybrid initialization

      fmg initialization

      high speed numerics enabled

       

       

    • imungan
      Subscriber

      Roe Scheme

      Implicit - Steady State

      Gradient: Least squares cell based

      flow: 2nd order

      under-relaxations are default

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