Velocity Boundary Condition
 

Hello everyone,
I want to setup a farfield velocity boundary condition with the flowing demand:
U = 1
V zeroGradient
W zeroGradient

as for the generic openfoam BC, there would be only either fixedValue and zeroGradient type. But my demand is both combined. So if anyone knows whether there is such implemented boundary condition as I wished?

Thanks very much
YX

I find out that the directionMixed can do the job. But I am not sure how to set the valueFraction, if anyone knows it?

type directionMixed;
refValue uniform (1 0 0);
refGradient uniform (0 0 0);
valueFraction uniform (1 0 0 0 0 0);
value uniform (1 0 0);