How is the characteristic length of open channel flow calculated?

- February 2, 2024 at 7:39 am
  
  Yiqing zhang
  Subscriber
  
  Y+ needs to be calculated when drawing the grid, so the value of the feature length needs to be known. I want to know whether the feature length of open channel flow is calculated by hydraulic radius or hydraulic diameter? Can you give specific formulas for reference?
- February 2, 2024 at 11:15 am
  
  Rob
  Forum Moderator
  
  You also need to avoid excessive aspect ratios when looking at VOF. So inflation meshes tend not to be recommended.
  - February 12, 2024 at 6:49 am
    
    Yiqing zhang
    Subscriber
    
    You didn't answer my question, did I not describe clearly enough?I want know
    how is the characteristic length of open channel flow calculated?
- February 12, 2024 at 10:23 am
  
  Rob
  Forum Moderator
  
  In much the same way as it's calculated in any other model. However, y+ is very much not the only criteria to worry about hence my comment. Depending on what the open channel is you may also want to think about how wall roughness interacts with the near wall cell.
  I'll also remind you about the T&Cs. Specifically sections regarding politeness. Written language is often misunderstood, so extra care should always be taken.