In the process of filtration,fluid impurities precipitate/accumulate;this results in an uneven inner wall of the filter,consequently leading to non-uniform sucfion/injecton.The Riemannian-Liouville fractional derivative model is used to investigate viscoelastic incompressible liquid food flowing through a permeable plate and to generalize Fick's law.Moreover,we consider steady-state mass balance during ultrafiltration on a plate surface,and a fractional-order concentration boundary condition is established,thereby rendering the problem real and complex.The governing equation is numerically solved using the finite difference algorithm.The effects of the fractional constitutive models,generalized Reynolds number,generalized Schmidt number,and permeability parameter on the velocity and concentration fields are compared.The results show that an increase in fractionalorder α in the momentum equation leads to a decrease in the horizontal velocity.Anomalous diffusion described by the fractional derivative model weakens the mass transfer;therefore,the concentration decreases with increasing fractional derivative γ in the concentration equation.