There are two different situations: 1) The flow demands solving the viscous sublayer: – This situation includes those cases where the wall-bounded effects are very important. Common examples are heat transfer, aerodynamic drag, pressure drop, flows with adverse pressure gradients… – To solve the viscous sublayer, the mesh must have a y+ < 1. 2) The flow does NOT demand solving the viscous sublayer: - These are cases where the wall-bounded effects are secondary, or where the flow undergoes geometry-induced separation. A typical example is the flow surrounding a bluff body. - To solve this cases the first cell close to the wall should have a y+ value within 30-300.