The CFD simulations were performed to gain insight into the boundary layer and shear stress behavior in the flow cell. The simulations provide boundary layer characteristics in the flow cell as a function of the inlet gauge pressure and flow regime and confirm the uniform shear stress distribution on the test surface. Figure S1 shows the 3D model of the flow cell. The computational domain includes a cylindrical inlet, transition section, and the 1 mm high test section enclosed by microscope glass slides. The inlet section has an inner diameter of 7 mm and a length of 15 mm. The transition section converts the flow from the round inlet to the rectangular test section with minimum changes in the cross-sectional area to avoid the onset of flow instabilities; it has a length of 45 mm. The test section is confined by two microscope glass slides and is 75 mm long and 25 mm wide. The main parameter in the mesh optimization is the CFD's ability to resolve the boundary layer, specifically the viscous sublayer to capture the wall shear stress. The viscous sublayer is defined by a non-dimensional wall distance of 𝑦 + = 5. To resolve the flow in the viscous sublayer, we use at least three cells within this region, with the first grid point located at a distance of 𝑦 + ≈ 1. The computational domain mesh consists of quadrilateral elements. The typical height of an element near the wall of the flow cell surface is about 4 microns. After conducting a mesh independence study, the sufficient number of elements is found to be around one million.

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