Protein Film Electrochemistry (PFE) is a technique in which an enzyme is directly wired to an electrode and its catalytic turnover rate is measured under the form of an electrical current. This technique has proved useful for the study of a number of enzymes, but requires fast transport of the enzymatic substrate towards the electrode. In a previous work (Fadel et al, Phys. Chem. Chem. Phys., 2019, 21, 12360), we have proposed a new design based on the wall-tube electrode that provides better transport than the rotating disc electrode, which is usually employed for PFE studies. In the present work, we use computational fluid dynamics to explore the effects of the various parameters of the cell, and propose a semi-empirical formula suitable to predict the mass-transport coefficient and the wall shear stress on the electrode. We use a 3D-printed cell to experimentally validate our predictions.