When further looking into the Fluent output, I noticed that the mesh is remeshed in the first iteration of the timestep in which the sudden jump in flow occurs. The output looks like:nThe part indicated in red is a part that I haven't seen before. Taking a closer look at my remeshing parameters, I saw that I didn't enable regional remeshing. I think this causes the cell skew after remeshing to be higher than the maximum cell skew specified (0.8, see below). nI also saw that there's an option to adjust the maximum skewness for the smoothing algorithm. The same part of my journal with the regional remeshing and the maximum skewness for the smoothing algorithm now looks like:nI think this may resolve my problem in this simulation, but I'm curious about your ideas!nBest regards,nJudithn