A measurement system for determining a physical parameter of a pipe-fluid system, comprising: a pair of confining elements (112, 114) configured to decrease surface vibration deformations at each end of the pipe-fluid system; an excitation system, configured to generate a mechanical vibration spectrum at a surface of the pipe-fluid system; and a vibration measurement device configured to be mechanically coupled to an outer surface of the pipe-fluid system, and configured to provide a mechanical vibration spectrum of the pipe-fluid system, wherein the confining elements (112,114) are configured to decrease surface vibration deformations at an outer surface of a pipe-fluid system, characterized by each confining element further comprising: a supporting frame configured to be detachably mounted on a pipe of the pipe-fluid system; and a fixation element configured to be detachably mounted for mechanically coupling the supporting frame with an outer surface of the pipe, wherein the confining element (112, 114) is configured to create a defined nodal point of the pipe vibrations at the location of the confining element suppressing radial and bending vibration modes locally all around the circumference of the pipe, wherein a mechanical vibration spectrum of the vibration modes of the pipe section between the confining elements can be used for the determination of the physical parameter. a pair of confining elements (112, 114) configured to decrease surface vibration deformations at each end of the pipe-fluid system; an excitation system, configured to generate a mechanical vibration spectrum at a surface of the pipe-fluid system; and a vibration measurement device configured to be mechanically coupled to an outer surface of the pipe-fluid system, and configured to provide a mechanical vibration spectrum of the pipe-fluid system, wherein the confining elements (112,114) are configured to decrease surface vibration deformations at an outer surface of a pipe-fluid system, characterized by each confining element further comprising: a supporting frame configured to be detachably mounted on a pipe of the pipe-fluid system; and a fixation element configured to be detachably mounted for mechanically coupling the supporting frame with an outer surface of the pipe, wherein the confining element (112, 114) is configured to create a defined nodal point of the pipe vibrations at the location of the confining element suppressing radial and bending vibration modes locally all around the circumference of the pipe, wherein a mechanical vibration spectrum of the vibration modes of the pipe section between the confining elements can be used for the determination of the physical parameter. a supporting frame configured to be detachably mounted on a pipe of the pipe-fluid system; and a fixation element configured to be detachably mounted for mechanically coupling the supporting frame with an outer surface of the pipe, wherein the confining element (112, 114) is configured to create a defined nodal point of the pipe vibrations at the location of the confining element suppressing radial and bending vibration modes locally all around the circumference of the pipe, wherein a mechanical vibration spectrum of the vibration modes of the pipe section between the confining elements can be used for the determination of the physical parameter.