What deficiency and advantage have node-based and cell-centred patterns for control-volume discretisation of transport equation on unstructured grids ?

Well, for the same tetrahedral mesh for example, you get to compute the solution at 5 times more points using cell-centered calculations compared to vertex centered methods: more CPU time, more accuracy, more memory requirements,... it depends on what price you want to pay for your runs. With a cell-centered formulation, the control volume is straightforward: the cell volume and faces. Otherwise, you have to define faces that separate nodes, etc... I think CFX5 is node centered for instance...

Fred.