A centrifugal filtration unit operating at a rotational speed of w has inner surface of the liquid (density ρL) located at a radial distance R from the axis of rotation. The thickness of the liquid film is δ and no cake is formed. The initial pressure drop during filtration is

• ½w2 . R2 . ρL
• ½w2 . δ2 . ρL
• ½w2 . δρL (2R + δ)
• ½w2 . R . ρL(R + 2δ)