.ClaRa.SubSystems.Furnace.HopperSlice_L4_AdditionalAir.MechanicalEquilibrium_FTW .ClaRa.SubSystems.Furnace.HopperSlice_L4_AdditionalAir.MechanicalEquilibrium_FTWmodel MechanicalEquilibrium_FTW = ClaRa.Basics.ControlVolumes.Fundamentals.SpacialDistribution.Homogeneous_L4;