Update INSFVTKESourceSink.md idaholab#27800 idaholab#27887 idaholab#2…

…7888

modules/navier_stokes/doc/content/source/fvkernels/INSFVTKESourceSink.md

@@ -59,6 +59,8 @@ incremental fixed-point search algorithm.
 The cells belonging to the `sub-laminar` boundary layers are defined as those
 for which $y^+ < 11.25$.
 The ones belonging to the `logarithmic` boundary layer are those for which $y^+ \ge 11.25$.
+The imposed threshold of $y^+ = 11.25$ is given by the value of $y^+$ at which the `sub-laminar`
+and `logarithmic` boundary profiles intersect.
 
 In the `sub-laminar` region production of turbulent kinetic energy is negligible, therefore, if $y^+ \lt 11.25$: