Fluids

Fluids

Error – Fluent solver – Floating point exception – Divergence detected

    • nagasudhan
      Subscriber

      When I tried creating solidification/melting model for phase change materials(PCMs) , I ended up with following error message 


      Boundary conditions used:


      1. Inlet - Mass-flow inlet - 3kg/s, Temp - 363K


      2. outlet - pressure outlet - 101325 pa (gauge pressure)


      Material property:


      1. PCM solidus temp, liquidus temp : 494 K, 511K


      2. Water: Fluent default


       


      Error message:


      ter continuity x-velocity y-velocity z-velocity energy time/iter


      32 1.7098e+09 4.6928e-01 1.8290e-01 3.1616e-01 1.6942e-04 0:00:12 1


      Stabilizing temperature to enhance linear solver robustness.


      Stabilizing temperature using GMRES to enhance linear solver robustness.


      temperature limited to 1.000000e+00 in 1013 cells on zone 7 in domain 1


      temperature limited to 5.000000e+03 in 5428 cells on zone 7 in domain 1


      temperature limited to 1.000000e+00 in 23995 cells on zone 6 in domain 1


       


      temperature limited to 5.000000e+03 in 38774 cells on zone 6 in domain 1


      Reversed flow on 67 faces (67.6% area) of pressure-outlet 10.


      (update-animation-object "animation-1")()


      Flow time = 33s, time step = 33


      167 more time steps


      Updating solution at time level N...


      done.


      iter continuity x-velocity y-velocity z-velocity energy time/iter


       


      33 2.4241e+11 4.9479e-01 1.9709e-01 2.6575e-01 1.5073e-01 0:142 1


       


      Stabilizing x-momentum to enhance linear solver robustness.


      Stabilizing temperature to enhance linear solver robustness.


      Stabilizing temperature using GMRES to enhance linear solver robustness.


      Divergence detected in AMG solver: temperature


      Reversed flow on 52 faces (53.6% area) of pressure-outlet 10.


      Divergence detected in AMG solver: temperature


      Error at host: floating point exception


      Error at Node 0: floating point exception


      Error at Node 1: floating point exception


      Error at Node 2: floating point exception


      Error at Node 3: floating point exception


      Compute processes interrupted. Processing can be resumed.


      Error: floating point exception


      Calculation complete.


       


      Attached images showing Liquid - fraction of PCM balls


       



    • nagasudhan
      Subscriber

    • RK
      Ansys Employee

      Hello,


      What is the courant number you have specified? Are you using "Higher Order Term Relaxation" option? 


      Regards,


      Rahul 

    • nagasudhan
      Subscriber

      I didn't specify any courant number, it should be default and relaxations factors are assigned by fluent, I have attached a screenshot below.


      Relaxation method - Gauss seidel


       


    • Rob
      Ansys Employee

      To rephrase Rahul's question. For the given time step, what is the Courant Number? 

    • nagasudhan
      Subscriber

      Courant number is set default. It is 500 for this case


      Solver setup is coupled.

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