DirectionMixed BC problem
 

HI,
we know directionMixed Bc's for vector fields is

type directionMixed;
refValue uniform (ux uy uz);
refGradient uniform (dUx dUy dUz);
valueFraction uniform (XX XY XZ YY YZ ZZ);
then what if i have a scalarField S instead

for example below:

type directionMixed;
refValue uniform 1;
refGradient uniform 0;
valueFraction uniform (0 0 0 1 0 0);
How this can be explained?

Is it that the value of S in the YY direction is fixed and equal one !!!!! ???
however S is a scalar.

help please?

thanks