creates a clear area 398 along the periphery of the obstruction 390 where the radial velocity will slow down and where any concentrated jets leaving the driving face of the vanes 392 can be spread out over the clear area 398 of the surface of obstruction 390 fig1 also depicts a centrifuge bowl 450 a conveyor hub 452 a pool surface 454 and a pool radius 456 as depicted in fig1 a liquid flow obstruction 400 is provided with a plurality of circumferentially spaced vanes 402 that are forwardly curved with respect to machine rotation so that the momentum along the driving face in the radial direction is reduced the momentum is passed to the tangential direction when the curved vanes 402 end at a radius 404 less than the radius 406 of the obstruction 400 a clear portion 408 of the obstruction 400 further allows spreading of the flow across the entire circumference of the obstruction 400 these two provisions further enhance the function of the liquid flow obstruction 400 in bringing the flow to a larger radius with higher g facilitating a shorter distance for heavier phase solids to settle to the bowl wall and increasing the radial settling speed with the radial component of the main flow as shown in fig4 reducing flow resistance with the vanes 402 on the upstream face of the obstruction 400 yet reducing also the negative impact from possible strong radial momentum from jets adjacent to the vanes fig1 also depicts a centrifuge bowl 458 a conveyor hub 460 a pool surface 462 and a pool radius 464 disks with upstream vanes can be installed for solid blade conveyors as well as for ribbon blade conveyors accordingly as illustrated in.