velocity field function at the inlet of T junction
 

Dear all,
I want to specify velocity vector for the water at the T junction inlet. the water move upward vertically for the distance of 0.163m and then the direction is change horizontally to the downstream pipe outlet. I specified the initial boundary condition as follow:
[($$Centroid[1]>0.2)?4.118:0.698,0.0,0.0]
above the 0.2 m is air inlet and the 4.118 m/s is the air velocity

also for the volume fraction:
($$Centroid[1]<0.2)?1:0
below 0.2 is occupied by water and above 0.2 is occupied by air

but when I used this field function for the water at the inlet I realized that the water velocity was increased, the field function:

[($$Centroid[1]< 0.2)?0.698:0.0,0.0,0.0]

for the air there is no problem since it's flow on the horizontal section
but the problem for the water because it moved vertically first for 0.163 m and then flow horizontally.

any suggestions are highly appreciated,

thanks in advance