Fluctuating residuals

- June 9, 2022 at 7:04 am
  
  vsjay3
  Subscriber
  
  Hi All,
  In Ansys Fluent, I am modelling a pipe (with water flowing inside) passing though a soil block. As boundary conditions, I assigned top wall surface of soil block a fixed temperature of 70C and bottom wall a fixed temperature of 32.2C. However, when I ran the simulation for 800 iterations, I found something interesting. The residuals (especially the energy residual) started fluctuating. The temperature results seem to make sense though. So should I not worry about the residual fluctuation? Also why do you think it is fluctuating?
  
  Your kind advice would be highly appreciated!
  
  Thank you very much!
- June 9, 2022 at 9:55 am
  
  DrAmine
  Ansys Employee
  
  Yes I will worry about the residual flucations as juding convergence will require not only monitoring key variables but aslo assissing numerical convergence in terms of residual and imbalances.
  
  Which model settings are you using?
  What about mesh quality?
  What about mesh resolution?
- June 9, 2022 at 1:11 pm
  
  Rob
  Ansys Employee
  
  What are the flow boundaries?

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