fluid Dynamics Consultancy
Computational Fluid Mechanics (CFD)
The numerical simulation of flow employing computerised fluid mechanics technology (or CFD) is playing an increasingly greater role in many technical applications. Over the last 15 years, numerical simulation has gradually replaced the experimental methods used for so long in proven areas such as aerospace engineering. CFD is now applied in virtually all areas of engineering, including mechanical, chemical and process engineering and medical technology.
Computational Fluid Dynamics (CFD) makes it possible to perform detailed calculations for any system that involves fluids, by solving basic equations for the conservation of materials, energy and quantity of movement for the particular geometry of each system under consideration. The results obtained consist of the values of all the variables that characterise the system (speed, pressure, temperature, composition, etc.) at each point of the system.
In many problems the fluid dynamics involved are key to optimising a technology (for example, reducing the aerodynamic resistance of a car, improving the efficiency of a compressor or the actions of a chemical reactor). Based on these simulations, it is possible to study aspects related to three-dimensional flow, such as heat transfer and mixing, together with radiation, combustion of dispersion of emissions. Simulations provide a new perspective of the problem that traditional methods are unable to provide.
A CFD simulation consists of 4 stages: generation of a 3D model, meshing of the domain, solving the equations and analysis of the results. Further information at Stages of a CFD simulation.
Examples of projects:
- Environment:
- Dispersion of odours from a chimney on a typical summer’s day in a Spanish city.
- Architecture:
- Simulation of the renewal of air in an office building with the inclusion of thermal loads such as people, computers, etc. Study of the seasonal impact
- Calculation of the temperature and ventilation field in a cinema. Analysis of the influence of the public
- Chemistry and processes:
- Basic studies on breakage and interaction between bubbles. The importance of such interfacial phenomena is essential in the majority of chemical reactors
- Optimisation and modelling of the aspiration, forming and deposition of glass fibre panels for insulation
- Optimisation of the configuration in an agitated reactor with a lower gaseous distributor
- Defence:
- Design of elements that involve plasma and ions. Simulation of the interaction of the electrical field and fluid dynamics over the ions is essential
Experimental techniques in fluid mechanics
Numerical simulation of a certain system may not be the best option in some cases. Despite the exponential growth in hardware and software in recent years, it is still not possible to successfully tackle many common problems with CFD. The reasons for this are diverse and we need to be aware of the limitations of CFD. Experimentation is usually an ideal complement when adjusting models or for providing information that is not included in simulations.
In such cases, it is necessary to resort to experimental techniques in order to obtain quantitative or qualitative measurements of speed, pressure, temperature, concentration, phases, etc. Normally the operating conditions, size of the installations or practicality make it impossible or very difficult to obtain a direct measurement of the variables of interest, and it is therefore necessary to resort to laboratory installations that are able to reproduce the phenomena to be studied. A change in the scale or operating conditions, for example, introduce distortions with the result that the equations that govern one process or another are not exactly identical.
The measurement techniques are very diverse and current technology has dramatically increased the quantity of equipment and instrumentation available. In fluid mechanics the specific and decorrelated measurement of its environment is only useful in average measurements, however it is normal for flows to be turbulent and for there to flows associated with turbulence that have an impact. Consequently, what could be termed global techniques, which provide information for an entire fluid region, are sought. These may be specific measurements (hot wire or LDV, Laser Doppler Velocimetry) based on a phase average or PIV (Particle Image Velocimetry) type zonal measurements. Direct visualisation or via PLIF (Planar Laser Induced Fluorescence), Schlieren, smoke, ink or oil film is normally an excellent technique whenever it can be used.
We have made strategic alliances with various institutions for the purposes of collaboration and having highly specific installations at our disposal (e.g. Wind tunnels) or the majority of instrumentation (lasers, special cameras, etc.). For example we have access to an atmospheric boundary aerodynamic tunnel (EESCLAT), another aerodynamic tunnel and a water tunnel, all three located in the DEQ of the URV and in an equipped laboratory at the CTQ (Chemical Technology Innovation Centre), among others.
