Meshing for y+ < 1, how to set the Estimated wall distance i.e. the First Boundary Cell Layer Thickness

I work with OpenFOAM on external flows an need exact drag results. The tutbulence models used require a boundary layer mesh in line with y+ < 1. For y+ < 1, the required thickness of the first layer of the boundary layer mesh on the object surface called the “Estimated wall distance” is calculated.

The “Estimated wall distance” can be calculated with this tool: CFD Online - Y-Plus Wall Distance Estimation

How can I set the thickness of the very first boundary mesh layer to this value?

All the tutorials talk about setting the overall boundary layer thickness and/or the number of boundary layers and a “growth factor” defining increase of the thickness of each layer from layer to layer but the actual requirement is to define the absolute thickness of the very first layer and a thickness increase factor of the following n layers. Can this be done?


Try different nb cells + expansion ratio + height of the BL, you can measure the height of the first cell easily with the post process tools of Salome.
Distance between 2 nodes that you can select directly on your mesh will do the job.
Remember that you need the half of the first cell for y+=1

Best regards