Papers by Antonio García-Olivares
Mathematics and Computers in Simulation, 2002
Physics of Fluids, 1998
The instability growth leading to a liquid sheet breakup has been studied with the objective of i... more The instability growth leading to a liquid sheet breakup has been studied with the objective of improving the understanding of the fundamental mechanisms of atomization. A three-dimensional Lagrangian code based on vortex dynamics methods has been implemented to track the air/liquid interfaces treated as inviscid vortex sheets. The results of these numerical simulations indicate a possible explanation for the presence of transverse and longitudinal filaments observed in liquid sheet air-assisted atomization experiments.
Water Research, 1995
A mathematical model has been developed and calibrated for a two-stage (A + B) activated sludge p... more A mathematical model has been developed and calibrated for a two-stage (A + B) activated sludge pilot plant treating wastewater from a chemical-pharmaceutical industry. Two series of simulations have been performed: (a) by using typical values for the parameters of the model from the bibliography, which remain constant with time, and (b) by using, for some parameters, values which are variable with time, and are determined following a specific methodology. The calibration is constrained to be exactly consistent with daily observations of COD from the effluent and reactor suspended solids (MLSS). Three internal parameters of the system were thus obtained in their daily variation: MLSS growth rate, specific substrate removal rate and concentration factor in the settling tank. Mean values obtained for MLSS growth rate were 0.73 d ~ and 0.022d -~ for reactors A and B respectively, and the average observed biomass yield coefficient was 0.38 (reactor A) and 0.21 (reactor B). The model infered the evolution of the COD and MLSS with a fairly good accuracy, proving that the method used to obtain the parameters does not have internal inconsistencies and may be used in other situations.
Water Research, 1995
A mathematical model has been developed and calibrated for a two-stage (A + B) activated sludge p... more A mathematical model has been developed and calibrated for a two-stage (A + B) activated sludge pilot plant treating wastewater from a chemical-pharmaceutical industry. Two series of simulations have been performed: (a) by using typical values for the parameters of the model from the bibliography, which remain constant with time, and (b) by using, for some parameters, values which are variable with time, and are determined following a specific methodology. The calibration is constrained to be exactly consistent with daily observations of COD from the effluent and reactor suspended solids (MLSS). Three internal parameters of the system were thus obtained in their daily variation: MLSS growth rate, specific substrate removal rate and concentration factor in the settling tank. Mean values obtained for MLSS growth rate were 0.73 d ~ and 0.022d -~ for reactors A and B respectively, and the average observed biomass yield coefficient was 0.38 (reactor A) and 0.21 (reactor B). The model infered the evolution of the COD and MLSS with a fairly good accuracy, proving that the method used to obtain the parameters does not have internal inconsistencies and may be used in other situations.
The sinking of the Prestige supertanker off the coast of Spain in November 2002 led to one of the... more The sinking of the Prestige supertanker off the coast of Spain in November 2002 led to one of the most devastating oil spills ever worldwide. Between 13,800 and 37,500 tons of oil still remain inside the wreckage. The mid-range and long-term behaviour of oil temperature and leaks were analysed to decide whether the oil could be pumped out in the current conditions. Past and present conditions near the wreckage were analysed, considering depth, water pressure, estimated oil behaviour inside the tanks, and possible future hull corrosion. A similar analysis may be useful in the management of future wreckages.
Journal of Contaminant Hydrology, 1993
. A model for the behaviour of ~37Cs in watershed scenarios. In: J.I. Kim and G. de Marsily (Edit... more . A model for the behaviour of ~37Cs in watershed scenarios. In: J.I. Kim and G. de Marsily (Editors), Chemistry and Migration of Actinides and Fission Products. J. Contam. Hydrol., 13: 183-211. A mathematical model of radiocesium transfer in a lake and its catchment is presented in an attempt to improve previous approaches. The experimental data base of the Esthwaite Water location, U.K., prepared in the international program on VAlidation of Model Predictions (VAMP) of IAEA/CEC, was used as a test scenario. Radiocesium enters the lake via: (l) a quick pulse of atmospheric deposition for 1-2 days; and (2) a lasting but smaller contribution from the catchment carried by the water runoff and the dragged sediments. An auxiliary model of the catchment was used to quantify these two source terms. The temporal evolution of the ~37Cs concentration in this lake after the contamination by the Chernobyl accident is modelled using a compartmental approach following the Codell model. The desorption/adsorption dynamics between water and sediments are considered both in the drainage water and in the lake boundary layer. The most important processes transferring contamination out of the lake water are adsorption of radioactivity by suspended sediments and their sedimentation; these processes are modelled through a distribution coefficient and through an aerial removal rate. Summer stratification is modelled introducing some auxiliary hypotheses. When using a priori probability distributions for the parameters based both on experimental evidence and on information from the literature the model simulates the observed radiocesium concentrations with an expected underprediction bias of 30% in the integrated concentrations in water. The concentration in sediments is inside the observed range in most of the runs. After the calibration of the model to the best fits observed with parameters inside their expected ranges, the bias decreases to -6% in the epilimnion, 8% in the hypolimnion and -4.4% in sediments, with an unexplained variance of _+ 3.2%, _+ 3% and _+ 1%, respectively.
Scientia Marina, 2004
The sinking of the Prestige supertanker off the coast of Spain in November 2002 led to one of the... more The sinking of the Prestige supertanker off the coast of Spain in November 2002 led to one of the most devastating oil spills ever worldwide. Between 13,800 and 37,500 tons of oil still remain inside the wreckage. The mid-range and long-term behaviour of oil temperature and leaks were analysed to decide whether the oil could be pumped out in the current conditions. Past and present conditions near the wreckage were analysed, considering depth, water pressure, estimated oil behaviour inside the tanks, and possible future hull corrosion. A similar analysis may be useful in the management of future wreckages.
A global alternative mix to fossil fuels is proposed, based on proven renewable energy technologi... more A global alternative mix to fossil fuels is proposed, based on proven renewable energy technologies that do not use scarce materials. The mix consists of a combination of onshore and offshore wind turbines, concentrating solar power stations, hydroelectricity and wave power devices attached to the offshore turbines. Solar photovoltaic power could contribute to the mix if its dependence on scarce materials is solved. The most adequate deployment areas for the power stations are studied, as well as the required space. Material requirements are studied for the generation, power transport and for some future transport systems. The order of magnitude of copper, aluminium, neodymium, lithium, nickel, zinc and platinum that may be required for the proposed solution is obtained and compared with available reserves. Overall, the proposed global alternative to fossil fuels seems technically feasible. However, lithium, nickel and platinum could become limiting materials for future vehicles fleet if no global recycling system were implemented and rechargeable zinc-air batteries could not be developed. 60% of the current copper reserves would have to be employed in the implementation of the proposed solution. Altogether, they may become a long-term physical constraint, preventing the continuation of the usual exponential growth of energy consumption.
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Papers by Antonio García-Olivares