A dynamic simulator for single-phase flow in piping & plants.


Single-phase flow systems are widespread in the industry (e.g. hydraulic or oleo-dynamic systems) and are subjected to a wide range of dynamic phenomena (e.g. transients, water hammers, internal resonances, resonances with the served systems). Very often these phenomena are critical to the main process (if the single-phase system is an auxiliary plant) or to the business (if the single-phase system is itself the main process).
The correct modelling and simulation of the flow system helps the engineers:

  • improving the design quality by testing the critical situations prior to the system starting up;
  • understanding and correcting anomalous behaviours in the running plant, by comparing the measured values with the expected ones and by trying different remedial actions.

Such “virtual” analysis by preventing problems or helping solving them always improves the general plant quality and often avoids expensive contract infringements or remedial actions.
HYDRODYN is a Matlab® / Simulink® based simulation software which provides the designer with a complete analysis of the liquid system. It is a cost-effective tool in the plant design and maintenance.
HYDRODYN is a complement of SATE’s simulation suite for the analysis of centrifugal and axial flow compressors (COMPSYS), in particular for the analysis of seals barrier fluid systems.

HYDRODYN plant scheme : example of oleo-dynamic system

HYDRODYN main window, clean and simple.


HYDRODYN uses a modified non linear formulation of the electro-acoustic analogy to model the dynamic fluid motion in pipes, by means of series of lumped volume and loss elements, which is suitable for turbulent low subsonic flow conditions (Mach << 1).
The plant model is built in Simulink® by connecting the easy-to-use blocks of the HYDRODYN library. The Simulink® model represents a set of ordinary differential equations (in the time domain) solved by the powerful and qualified MATLAB® kernel.
The HYDRODYN library includes:

  • lumped volumes and lumped losses blocks (0-D blocks);
  • non-linear tube blocks with built-in one dimension discretization (1-D blocks);
  • non-linear lumped accumulator blocks where the liquid is interfaced with a gas following its own thermodynamic laws (0-D blocks).

HYDRODYN provides the pressure, mass flow rate, temperature, volumes, valve opening and other magnitudes of interest for the various plant elements as result of the simulation. The outputs are delivered in easy-to-understand plots versus time.

Example of HYDRODYN result plots


HYDRODYN was derived from the fully validated ACUSYS program, another SATE application extensively used for pressure pulsation analyses in gas and liquid pipe systems. HYDRODYN has been tested and validated against comparison with existing machines, other commercial CFD codes, and theoretical solutions.


HYDRODYN runs into the Matlab® / Simulink® environment, and it is friendly interfaced to the user by graphic buttons and menu commands.


HYDRODYN is also used by SATE as a tool for engineering services provided to customers who wish not to enter the functions and details of the program. In this case the results of the simulations are produced in form of reports, together with comments and specifications for plant modifications.