Fluids

Fluids

Is the usage of energy under relaxation factor is correct?

    • Sowmiya
      Subscriber

      Hai,


      I have simulated steady state high temperature laminar flames with the chemical reaction. I have included the reactions and all the required Arrhenius parameters in the reaction panel. I followed the procedure as in the fluent manual. First the cold flow is created and disabled all the cold flow equations. Then volumetric reactions are activated and solved all the species. Later all the equations (i.e., species, energy and flow) are activated. While solving I reduced the under relaxed factor (URF) of energy to 1e-05 in order to increase the stability of the flow. And I got all the distributions of species included. Now, if I try to increase the URF, I find all the species distributions to get diffused.


      Whether reducing the energy URF value to 1e-05 is correct? or what should I do now?


      Please kindly give me few suggestions and your thoughts on it.

    • Rob
      Ansys Employee

      Energy URF should be 1 and should only be altered to about 0.97 if you really need to (unless the model default isn't 1 in which case take the default and leave it alone). 

    • Sowmiya
      Subscriber

      Thank you so much for the reply.


      As the oscillations of energy residual were large due to source terms added in the energy i had to reduce energy URF less than one to increase the stability of flow. 


      In order to increase the Energy URF to 1 what should i do now? 


       


      Please kindly give me few suggestions.


       


      Many thanks in advance.

    • Rob
      Ansys Employee

      How stable is the flame, and how good is the mesh? 

    • Sowmiya
      Subscriber
      n
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