POLYFLOW - how to define a moving boundary whose motion does not deform adjacent boundary sets?

Let us consider a transient flow situatoin where a border is moving, with the fluid attached at that border. How can this be modelled without generating deformations along the adjacent borders?
An easy remedy consists of defining slipping boundary conditions on the moving part, with a linear law (Navier law). In particular, a large coefficient should be selected while the desired wall velocity should be assigned. This mixed condition will usually not enter into conflict with the essential conditions defined on adjacent borders. When combined with Lagrangian remeshing, the border will move according to the specified velocity, while the adjacent borders will not. In particular, at the intersecton point between the moving border and the surrounding boundaries, the essential conditions will prevail.

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