i am working on a project for analysis of blood flow velocity in arteries (especially crooked arteries). the case study requires modelling of a control volume which can expand and contract periodically.

provided that time dependent state of the control volume is known (state of expansion or contraction) can a model be created on any of the CFD softwares.

i have been pondering on the idea of moving mesh, but it seems that the mesh can only change its pattern but not the size of the space which it fills. can there be any method through which this can be achieved. say---- by keeping axis (of the cylendrical conduit) as the reference and defining the motion of all the points with respect to that?

Use Junction Box Routine

"When this option is chosen, a user FORTRAN routine that explicitly sets the coordinates of all nodes in a given domain is specified and called. The Junction Box Routine that is called is specified with this mesh deformation option rather than with other Junction Box Routines on the Solver Controls panel of the Physics Editor. The specified routine is always called at the start of each time step, and all mesh coordinate dependent quantities (e.g. the volumes of control volumes) are automatically updated.The intended use of this mesh deformation option is demonstrated in the Fluid Structure Interaction and Mesh Deformation tutorial Fluid Structure Interaction and Mesh Deformation (p.in CFX-5 Tutorials)".