I recently had to help a friend setting up a case in OpenFOAM, where a ramp boundary condition for the velocity was required. Apparently OpenFOAM doesn’t offer this boudary condition, or at least it might seem so at a first impression. Actually, OpenFOAM offers a very general way to specify unsteady boundary conditions called timeVaryingFixedValue, which can read a data set from a text file, interpolate them with respect to time and use them to generate the unsteady boundary condition. I will show how to use this boundary condition with a simple example of a ramp for a velocity boundary condition. We want the velocity to ramp from the value…