Soliton-limited superflow in He-3-A between parallel plates

We have studied theoretically the flow of superfluid He-3-A in parallel-pla te geometry. The equilibrium order-parameter texture is calculated numerica lly in two spatial dimensions consisting of the coordinates along the flow direction and perpendicular to the plates. The calculations have been done using the hydrostatic theory in the Ginzburg-Landau region and assuming a l arge external magnetic field perpendicular to the plane of calculation. We have studied a uniform texture and a dipole-unlocked splay soliton as initi al configurations. In the former case we find the Freedericksz transition a nd a helical instability with increasing flow. In the latter case we find i nstability in the soliton. This instability is closely related to the criti cal velocity in the presence of a vortex sheet. Also, the transverse NMR fr equency shift at the soliton has been calculated.