recommended values for transition ratio/last ratio

- August 10, 2021 at 11:29 am
  
  vitus
  Subscriber
  
  Hi,
  im using the option last ratio to generate boundary layers in Fluent Mesh. So I can choose first cell hight, number of layers and last ratio. But Im not sure what to use here, to get a smooth transition and as many layers as possible. My cell size is about 1mm, but if I take 10 layers my final layer should be 7.31 mm, so this wont really fit.
- August 10, 2021 at 2:04 pm
  
  RK
  Ansys Employee
  
  Hello,
  I would recommend using a first height for the prism layer for these values and then adding 10 layers with default transition ratio. This recommendation is without actually looking at the mesh and the model. So, you can generate the mesh with this settings and check if the BL is good enough to capture the physics or check y+
- August 10, 2021 at 2:13 pm
  
  vitus
  Subscriber
  
  default is at 0.272... i thought something near 1 should be a smooth transition?