Design of an asymmetrical flow field-flow fractionation cell with both mean channel and membrane velocities constant

We consider an asymmetric flow-field-flow fractionation (FFF) cell with an exponential variation of the channel breadth and a hydraulic conductivity gradient membrane to get a constant efficiency of the separation process over the whole length of the channel. After presenting the model for a membrane of constant hydraulic conductivity, we determine the dependence of conductivity with distance to entrance to get both mean channel and membrane velocities constant.