Here is our second preview on new features in TwinMesh™ 2018: CFX Berlin implemented a mesh interpolation method in User Fortran. So far, the time step size of the CFD simulation has to be set according to the desired revolution speed and the prescribed angle increment of the pre-generated meshes from TwinMesh. Now it is possible to set an arbitrary time step size, and the corresponding mesh is calculated with a spline interpolation between the pre-generated meshes at run-time. This can also be used for non-uniformly rotating positive displacement machines. The animation shows a roots blower compressing from 1 to 1.2 bar. Initial rotational velocity is 400 rev/min, then it changes in 0.15 seconds to -400 rev/min and back to 400 rev/min so that the rotors oscillate around medium position by approx. 57°. Animation shows velocity on left as colors and direction as arrowheads, and pressure at right. The meshes were generated with TwinMesh with an angle increment of 1°, time step size was set to 0.417 ms so that rotation increment is also 1° at 400 rev/min, but clearly much lower between.