This variable by default is not available in moving mesh domains, as it will be incorrect for cases in which the mesh is deforming, i.e. the mesh moves relative to the associated wall. In such a case the integrated quantity would be moved to a different/wrong location on the wall. Thus, the integrated wall mass flow of particles can only be correct when the mesh is stationary on the wall. This is the case when i.e. the whole domain is moving and the mesh motion on the walls is defined as “Stationary”. For such cases the variable can be made available with the following expert parameter: FLOW: Flow Analysis 1 EXPERT PARAMETERS: pt mm time integrated bnd vertex arrays = t END END