The following thesis discusses two separate microfluidic applications analysed with ANSYS Fluent 2022R1. For a rotating capillary tube of a diameter of 2 mm and height of 10 mm that is filled with air on the top half and water on the bottom half $(Bo_g=\frac{\Delta\varrho g L^2}{\sigma}\approx0.543)$ applying different rotational velocity profiles to the cylinder wall was found to not have a significant impact on the fluid interface. The geometry was replicated with a 2D axisymmetric model and analysed with and without the effect of gravity, trying different stabilization methods and settings. For constant time stepping the instability region was identified, for adaptive time stepping the results showed an almost complete independence from the imposed wall speed.