  Magnetic fields advected along with low angular momentum accretion flows
predominantly become toroidal due to the strong azimuthal velocity close to a
black hole. We study self-consistently the movements of these flux tubes inside
an advective disc and how they dynamically influence the flow. We find that the
centrifugal barrier slows down the radial motion of the flux tubes. In this
case, the large magnetic flux tubes with a significant drag force escape along
the vertical axis due to buoyancy. Magnetic pressure rises close to the black
hole and together with the centrifugal force, it combats gravity. The
tug-of-war among these forces causes the centrifugal pressure supported shock
to oscillate radially. We study the effects of successive injection of flux
tubes and find how the flux tube could be trapped inside the disc in regions of
highest entropy. Most interestingly, the shock wave remains at its average
location and is not destroyed. We show that the toroidal field loops contribute
significantly to collimate and accelerate the outflows from the centrifugal
barrier and suggest this mechanism to be a way to collimate and accelerate
jets.
