Y+ should be considered even for laminar flow?

Kentyn

Hi, everyone,

We have discussed in the Forum a lot on the YPLUS treatment for turbulence modeling. Now I learned (see below) that the Y+ considration shlould taken even for the laminar flow. This is new for me.

It is strange because I knew the log-law for the "law-of-the-wall" was used for identifying the viscous layer,blending layer, and the fully turbulent layer. Therefore, it will be applicable for turbulent case. However, according to the statement below, it seems to come to a conclusion that all viscous models need to take care of the choice of YPLUS. This point is not clear to me.

Could any one clarify WHY? Hope to get your comments.

--------------------------------------------------------- There are certain specific recommendations for first cell height (Yp). Resolution of the boundary layer plays a significant role in the accuracy of the computed wall shear stress and heat transfer coefficient. This is particularly true in laminar flows where the grid adjacent to the wall should obey

Yp* Sqrt (Uinf/Mux) <= 1

where, Yp is the distance to the wall from the adjacent cell centroid; Uinf is the free-stream velocity; Mu is kinematic viscosity of the fluid and x is distance along the wall from the starting point of the boundary layer

Proper resolution of the mesh for turbulent flows is also very important. In the near-wall region, different mesh resolutions are required depending on the near-wall model being used.