dear sir i am dveloping a code for simulation of mould filling. i want use slip condition .but i dont know what is it. in boundary the control volume is half. please sombody describe me what i should do in u b.c and v b.c(boundary condition) thanks

For slip condition, you have two kind of bc: 1. In normal direction, you have velocity equal 0, so, n.v=0, where n is the unit normal vector, and v is velocity vector.

2. In tangent direction, your tangent stress is 0, so, tn:T=0, where t is the unit tangent vector, and n is the unit normal vector, T is the stress tensor.

If you need partially slip condition, the bc number 2, it's 1/b*t.(v-v_w)=tn:T, where b is the slip coefficient.