Fluids

Fluids

Simulating both internal and external flow at the same time?

    • Atgeirr
      Subscriber
      Hello there everyone,nI'm trying to simulate an exhaust system for a motorcycle as complete as possible. As of right now I've successfully simulated to flow within the pipes and the heat transfer into the metal. However while driving a motorcycle the airflow traveling over the exhaust pipe will also cool the pipes down quite a lot. I would like to include this within my simulations but I honestly have no idea how to implement this. Best case scenario is that I could sim both internal and external in one go within Fluent but I doubt that's possible.nFrom my (rather limited) understanding K-w SST is not usable for external flow and it is the viscous model that has given me the best results for internal flow. Which made me think that the only solution is the connect the results from my internal sims to a new external sim. However there are a lot of smart people on this forum so I was hoping someone knows if it's possible to do both the internal and external flow at the same time within Fluent. nThank youn
    • Keyur Kanade
      Ansys Employee
      You can do internal plus external in one session. This would require you to include internal and external domain in single session. Mesh them in single session. Please note that this will increase the mesh count. If you want to use kw sst, please make sure that you have defined inflation correctly. Please use last ratio method and then use first height of 1/10th of surface mesh size. This will help you to get good y+ value. You can find similar many discussions on this forum. nRegards,nKeyurnHow to access Ansys Online Help DocumentnHow to show full resolution imagenGuidelines on the Student CommunitynHow to use Google to search within Ansys Student Communityn
    • Atgeirr
      Subscriber
      Thank you for your answer Kkanade.nKnowing it's possible to sim both internal and external will save me a lot of time at work. Even though that might seem counter-intuitive.nHowever I have a follow-up question:nI was taught to calculate my first layer height based on the desired Y+ of the viscous model (in this case 1
    • Keyur Kanade
      Ansys Employee
      1/10th size usually gives y+ close to 1. n
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