Computer-based system adapted to create a representation of mechanical and flow-mechanical function of a .delta.V-pump. A mathematical modeling algorithm is used based upon a transforming element adapted to connect different physical domains via a transforming value. The system comprises an upper transforming element (TF1) and a lower transforming element (TF2) each having a flow domain (fd1, fd2) and a mechanical domain (md1, md2), the upper transforming element is provided with a transforming value A1 and the lower transforming element is provided with a transforming value A1+A2, wherein A1 and A2>0. The upper and lower transforming elements are interconnected such that their mechanical domains are connected, said mechanical domains are provided with a control value representing a directional measure (F) arranged to intermittently and simultaneously activate said mechanical domains of the transforming elements. By interconnecting two .delta.V-pump representations the pumping action of a heart may be simulated.