Electric power generation, as well as many other industrial processes, often require disposing of certain amounts of thermal energy that cannot be used profitably. This requires cooling with waters that are eventually discharged into the sea, rivers or reservoirs. Other processes, like desalination, generate effluents with a composition that differs substantially from that of the receiving waters. Others, like the regasification of liquid gas, produce effluents cooler than the receiving waters. All such situations require studying the dispersion and mixing of the discharge in order to assess its impact on the environment.

Principia has conducted such analyses in all the situations described above. Parametric analyses are usually carried out, primarily to account for the inherently variable nature of many of the intervening factors, like the meteorological and oceanographical conditions.

In the example shown, the calculated surface temperatures are plotted together with the measurements taken from a boat. The second picture presents the same information, as obtained from thermal infrared imaging. The discharge shown is the cooling effluent from a nuclear power plant.

The Prestige tanker sank in November 2002 some 130 miles off the Galician coast. Repsol YPF accepted the request from the Spanish Government to solve the problem posed by the fuel still contained in the wreck almost 4 km below the surface.

Principia collaborated with Repsol YPF with a considerable number of support calculations. Such calculations included the structural evolution of ship during the sinking process and impact with the bottom, the simulation of the fuel behaviour in various alternative procedures for extracting the fuel and conveying it to the surface and the analysis of other physical problems associated with the ecovery of the fuel.

The first figure is a photograph of the ship not long before it sank; the other is an image, obtained by sonar scanning, of the bow fragment resting on the sea bottom.

The construction of underground works very often affects the subsurface flows and the freatic surface in the ground due to the barriers introduced by the construction. Particularly in urban areas, such effects must be limited to prevent flooding of basements, differential settlements, cracking problems, etc. The construction of new metro lines, as well as the burial of existing railway lines, are typical originators of these problems.

Principia has carried out this type of studies for new metro lines in cities like Valencia or Sevilla; in relation with the burial of railway lines in Logroño, Oliva, etc; and for other urban tunnels like the one under Plaza de Colón in Barcelona.

The following figures present an example. The first one shows the changes predicted in the freatic surface in a certain case in the absence of any remedial measures; the second one is similar, but now incorporating some measures to mitigate the barrier effect that the construction would impose on the subsurface flow.