DF - Dinàmica No Lineal de Fluids
http://hdl.handle.net/2117/1085
2017-03-29T03:38:26ZInertial waves in rapidly rotating flows: a dynamical systems perspective
http://hdl.handle.net/2117/102980
Inertial waves in rapidly rotating flows: a dynamical systems perspective
López Moscat, Juan Manuel; Marqués Truyol, Francisco
An overview of recent developments in a wide variety of enclosed rapidly rotating flows is presented. Highlighted is the interplay between inertial waves, which have been predicted from linear inviscid considerations, and the viscous boundary layer dynamics which result from instabilities as the nonlinearities in the systems are increased. Further, even in the absence of boundary layer instabilities, nonlinearity in the system often leads to complicated interior flows due to subcritical instabilities, Eckhaus bands and heteroclinic dynamics. The ensuing spatio-temporally complex dynamics is analysed in terms of equivariant dynamical systems, providing a general perspective for the wide range of dynamics involved.
2017-03-28T14:51:51ZLópez Moscat, Juan ManuelMarqués Truyol, FranciscoAn overview of recent developments in a wide variety of enclosed rapidly rotating flows is presented. Highlighted is the interplay between inertial waves, which have been predicted from linear inviscid considerations, and the viscous boundary layer dynamics which result from instabilities as the nonlinearities in the systems are increased. Further, even in the absence of boundary layer instabilities, nonlinearity in the system often leads to complicated interior flows due to subcritical instabilities, Eckhaus bands and heteroclinic dynamics. The ensuing spatio-temporally complex dynamics is analysed in terms of equivariant dynamical systems, providing a general perspective for the wide range of dynamics involved.Flexible rod design for educational wind balance
http://hdl.handle.net/2117/102821
Flexible rod design for educational wind balance
Raush Alviach, Gustavo Adolfo; Castilla López, Roberto; Gámez Montero, Pedro Javier; Wojciechowski, Jakub; Codina Macià, Esteban
This article provides a technical description of a flexible hinge for wind tunnel rigs. For academic purposes, the device was integrated into several rod flexures to build a home-made external wind balance system. The cylindrical elastic element incorporates several notches, and the flexure linkage is able to transmit force in the main axial direction without hindering perpendicular movement. The flexural element described here is simple and easily manufactured, and can also be used with other types of wind balance. The flexure described in this article has similar functionality to those mentioned in the reference section, but has a more compact element. The project's effectiveness was demonstrated in a series of experimental comparisons of forces and moments measured on a wing using the N.A.C.A. Clark-Y airfoil profile.
This is a copy of the author 's preprint version of an article published in the journal Experimental techniques. The final publication is available at Springer via http://dx.doi.org/10.1007/s40799-016-0017-9
2017-03-23T11:45:22ZRaush Alviach, Gustavo AdolfoCastilla López, RobertoGámez Montero, Pedro JavierWojciechowski, JakubCodina Macià, EstebanThis article provides a technical description of a flexible hinge for wind tunnel rigs. For academic purposes, the device was integrated into several rod flexures to build a home-made external wind balance system. The cylindrical elastic element incorporates several notches, and the flexure linkage is able to transmit force in the main axial direction without hindering perpendicular movement. The flexural element described here is simple and easily manufactured, and can also be used with other types of wind balance. The flexure described in this article has similar functionality to those mentioned in the reference section, but has a more compact element. The project's effectiveness was demonstrated in a series of experimental comparisons of forces and moments measured on a wing using the N.A.C.A. Clark-Y airfoil profile.The potential of the sea breeze for wind energy generation in peri-urban coastal areas using small wind turbines
http://hdl.handle.net/2117/102569
The potential of the sea breeze for wind energy generation in peri-urban coastal areas using small wind turbines
Rojas Gregorio, José Ignacio; Cabrera Agudo, Barbara; Mazón Bueso, Jordi
This work investigates the potential of the sea breeze for wind energy generation with small wind turbines. For this purpose, we used wind data recorded in the Llobregat Delta (NE of the Iberian Peninsula) from 1993 to 2010 and turbine power curves obtained from QBlade, FAST and AeroDyn freeware tools, and from the manufacturer. The HP-600W turbine, with hub-height 8 m, would deliver 126 kWh in a year (53 kWh during the sea breeze period, i.e., March 1 to September 30, 10 to 19h LT), with average power of 14 W (27 W). The results for the entire year agree with data measured in situ in 2015, but it is not the case for the sea breeze period. Therefore, more research is necessary to validate completely the proposed approach, and to confirm the real potential of the sea breeze for micro-generation in a peri-urban coastal area like the one under study, where large wind farms are not feasible.
2017-03-16T10:38:04ZRojas Gregorio, José IgnacioCabrera Agudo, BarbaraMazón Bueso, JordiThis work investigates the potential of the sea breeze for wind energy generation with small wind turbines. For this purpose, we used wind data recorded in the Llobregat Delta (NE of the Iberian Peninsula) from 1993 to 2010 and turbine power curves obtained from QBlade, FAST and AeroDyn freeware tools, and from the manufacturer. The HP-600W turbine, with hub-height 8 m, would deliver 126 kWh in a year (53 kWh during the sea breeze period, i.e., March 1 to September 30, 10 to 19h LT), with average power of 14 W (27 W). The results for the entire year agree with data measured in situ in 2015, but it is not the case for the sea breeze period. Therefore, more research is necessary to validate completely the proposed approach, and to confirm the real potential of the sea breeze for micro-generation in a peri-urban coastal area like the one under study, where large wind farms are not feasible.Periodic orbits in tall laterally heated rectangular cavities
http://hdl.handle.net/2117/102448
Periodic orbits in tall laterally heated rectangular cavities
Net Marcé, Marta; Sánchez Umbría, Juan
This study elucidates the origin of the multiplicity of stable oscillatory flows detected by time integration in tall rectangular cavities heated from the side. By using continuation techniques for periodic orbits, it is shown that initially unstable branches, arising at Hopf bifurcations of the basic steady flow, become stable after crossing Neimark-Sacker points. There are no saddle-node or pitchfork bifurcations of periodic orbits, which could have been alternative mechanisms of stabilization. According to the symmetries of the system, the orbits are either fixed cycles, which retain at any time the center symmetry of the steady flow, or symmetric cycles involving a time shift in the global invariance of the orbit. The bifurcation points along the branches of periodic flows are determined. By using time integrations, with unstable periodic solutions as initial conditions, we determine which of the bifurcations at the limits of the intervals of stable periodic orbits are sub- or supercritical.
2017-03-14T13:11:34ZNet Marcé, MartaSánchez Umbría, JuanThis study elucidates the origin of the multiplicity of stable oscillatory flows detected by time integration in tall rectangular cavities heated from the side. By using continuation techniques for periodic orbits, it is shown that initially unstable branches, arising at Hopf bifurcations of the basic steady flow, become stable after crossing Neimark-Sacker points. There are no saddle-node or pitchfork bifurcations of periodic orbits, which could have been alternative mechanisms of stabilization. According to the symmetries of the system, the orbits are either fixed cycles, which retain at any time the center symmetry of the steady flow, or symmetric cycles involving a time shift in the global invariance of the orbit. The bifurcation points along the branches of periodic flows are determined. By using time integrations, with unstable periodic solutions as initial conditions, we determine which of the bifurcations at the limits of the intervals of stable periodic orbits are sub- or supercritical.Maxwell equations in the Debye potential formalism
http://hdl.handle.net/2117/102159
Maxwell equations in the Debye potential formalism
Fayos Vallés, Francisco; Llanta Salleras, Estanislao; Llosa, J
The authors propose a method for computing the electromagnetic test-field created by a given distribution of charges and currents using the Debye potential formalism in curved space-times. This framework has been applied explicitly to the Schwarzschild case.
2017-03-08T18:24:18ZFayos Vallés, FranciscoLlanta Salleras, EstanislaoLlosa, JThe authors propose a method for computing the electromagnetic test-field created by a given distribution of charges and currents using the Debye potential formalism in curved space-times. This framework has been applied explicitly to the Schwarzschild case.Nonlinear and detuning effects of the nutation angle in precessionally-forced rotating cylinder flow
http://hdl.handle.net/2117/101564
Nonlinear and detuning effects of the nutation angle in precessionally-forced rotating cylinder flow
Lopez Moscat, Juan Manuel; Marqués Truyol, Francisco
The flow in a rapidly rotating cylinder forced to precess through a nutation angle a
is investigated numerically, keeping all parameters constant except a, and tuned to a
triadic resonance at a = 1º. When increasing a, the flow undergoes a sequence of well-
characterized bifurcations associated with triadic resonance, involving heteroclinic and
homoclinic cycles, for a up to about 4º. For larger a, we identify two chaotic regimes.
In the first regime, with a between about 4º and 27º, the bulk flow retains remnants of
the helical structures associated with the triadic resonance, but there are strong nonlinear
interactions between the various azimuthal Fourier components of the flow. For the larger
a regime, large detuning effects lead to the triadic resonance dynamics being completely
swamped by boundary layer eruptions. The azimuthal mean flow at large angles results in a
large mean deviation from solid-body rotation and the flow is characterized by strong shear
at the boundary layers with temporally chaotic eruptions.
2017-02-24T15:42:52ZLopez Moscat, Juan ManuelMarqués Truyol, FranciscoThe flow in a rapidly rotating cylinder forced to precess through a nutation angle a
is investigated numerically, keeping all parameters constant except a, and tuned to a
triadic resonance at a = 1º. When increasing a, the flow undergoes a sequence of well-
characterized bifurcations associated with triadic resonance, involving heteroclinic and
homoclinic cycles, for a up to about 4º. For larger a, we identify two chaotic regimes.
In the first regime, with a between about 4º and 27º, the bulk flow retains remnants of
the helical structures associated with the triadic resonance, but there are strong nonlinear
interactions between the various azimuthal Fourier components of the flow. For the larger
a regime, large detuning effects lead to the triadic resonance dynamics being completely
swamped by boundary layer eruptions. The azimuthal mean flow at large angles results in a
large mean deviation from solid-body rotation and the flow is characterized by strong shear
at the boundary layers with temporally chaotic eruptions.An exactly solvable model in P.R.M.: quantization. II
http://hdl.handle.net/2117/101439
An exactly solvable model in P.R.M.: quantization. II
Iranzo Fernández, Vicente; Llosa, J; Marqués Truyol, Francisco; Molina, A
The quantization of a priori hamiltonian predictive systems is studied. It is applied to quantize the family of N-particle relativistic models presented in ref. 1. The relativistic two-particle oscillator is studied in detail and finally our results are compared with others that already appeared in the literature.; On étudié la quantification de systèmes hamiltoniens pre-prédictifs a priori. Comme application, on quantifie la famille de modèles relativistes à N particules présentes dans la référence 1. On étudié en detail l’oscillateur relativiste a deux particules. Finalement on compare les résultats obtenus avec d’autres parus précédemment.
2017-02-23T09:37:44ZIranzo Fernández, VicenteLlosa, JMarqués Truyol, FranciscoMolina, AThe quantization of a priori hamiltonian predictive systems is studied. It is applied to quantize the family of N-particle relativistic models presented in ref. 1. The relativistic two-particle oscillator is studied in detail and finally our results are compared with others that already appeared in the literature.
On étudié la quantification de systèmes hamiltoniens pre-prédictifs a priori. Comme application, on quantifie la famille de modèles relativistes à N particules présentes dans la référence 1. On étudié en detail l’oscillateur relativiste a deux particules. Finalement on compare les résultats obtenus avec d’autres parus précédemment.Are the Pyrenees a barrier for the transport of birch (Betula) pollen from Central Europe to the Iberian Peninsula?
http://hdl.handle.net/2117/101352
Are the Pyrenees a barrier for the transport of birch (Betula) pollen from Central Europe to the Iberian Peninsula?
Izquierdo Miguel, Rebeca; Alarcón Jordán, Marta; Mazón Bueso, Jordi; Pino González, David; De Linares, Concha; Aguinagalde, Xabier; Belmonte Soler, Jordina
This work provides a first assessment of the possible barrier effect of the Pyrenees on the atmospheric transport of airborne pollen from Europe to the North of the Iberian Peninsula. Aerobiological data recorded in three Spanish stations located at the eastern, central and western base of the Pyrenees in the period 2004–2014 have been used to identify the possible long range transport episodes of Betula pollen. The atmospheric transport routes and the origin regions have been established by means of trajectory analysis and a source receptor model. Betula pollen outbreaks were associated with the meteorological scenario characterized by the presence of a high-pressure system overm over Morocco and Southern Iberian Peninsula. France and Central Europe have been identified as the probable source areas of Betula pollen that arrives to Northern Spain. However, the specific source areas are mainly determined by the particular prevailing atmospheric circulation of each location. Finally, the Weather Research and Forecasting model highlighted the effect of the orography on the atmospheric transport patterns, showing paths through the western and easternmost lowlands for Vitoria-Gasteiz and Bellaterra respectively, and the direct impact of air flows over Vielha through the Garona valley.
2017-02-21T17:22:07ZIzquierdo Miguel, RebecaAlarcón Jordán, MartaMazón Bueso, JordiPino González, DavidDe Linares, ConchaAguinagalde, XabierBelmonte Soler, JordinaThis work provides a first assessment of the possible barrier effect of the Pyrenees on the atmospheric transport of airborne pollen from Europe to the North of the Iberian Peninsula. Aerobiological data recorded in three Spanish stations located at the eastern, central and western base of the Pyrenees in the period 2004–2014 have been used to identify the possible long range transport episodes of Betula pollen. The atmospheric transport routes and the origin regions have been established by means of trajectory analysis and a source receptor model. Betula pollen outbreaks were associated with the meteorological scenario characterized by the presence of a high-pressure system overm over Morocco and Southern Iberian Peninsula. France and Central Europe have been identified as the probable source areas of Betula pollen that arrives to Northern Spain. However, the specific source areas are mainly determined by the particular prevailing atmospheric circulation of each location. Finally, the Weather Research and Forecasting model highlighted the effect of the orography on the atmospheric transport patterns, showing paths through the western and easternmost lowlands for Vitoria-Gasteiz and Bellaterra respectively, and the direct impact of air flows over Vielha through the Garona valley.Km-scale shoreline sand waves in the Western Mediterranean Sea
http://hdl.handle.net/2117/100709
Km-scale shoreline sand waves in the Western Mediterranean Sea
Falqués Serra, Albert; Ribas Prats, Francesca
A number of morphodynamic models have been developed to simulate the dynamics of large-scale bedform patterns on the continental shelf. Most of the models are based on linear stability analysis and, therefore, only describe the characteristics of the bedforms at their formation. Apart from studying the principal formation mechanism, the models have take into account various processes (three dimensional flows, sediment sorting, wave stirring, different tidal constituents, etc) to describe the characteristics of the bedforms at specific locations. Exploration of the finite amplitude regime have also been made with simplified models. Future model developments are needed to explore long-term dynamics.
2017-02-08T15:43:14ZFalqués Serra, AlbertRibas Prats, FrancescaA number of morphodynamic models have been developed to simulate the dynamics of large-scale bedform patterns on the continental shelf. Most of the models are based on linear stability analysis and, therefore, only describe the characteristics of the bedforms at their formation. Apart from studying the principal formation mechanism, the models have take into account various processes (three dimensional flows, sediment sorting, wave stirring, different tidal constituents, etc) to describe the characteristics of the bedforms at specific locations. Exploration of the finite amplitude regime have also been made with simplified models. Future model developments are needed to explore long-term dynamics.Km-scale shoreline sand waves
http://hdl.handle.net/2117/100708
Km-scale shoreline sand waves
Falqués Serra, Albert; Ribas Prats, Francesca
A number of morphodynamic models have been developed to simulate the dynamics of large-scale bedform patterns on the continental shelf. Most of the models are based on linear stability analysis and, therefore, only describe the characteristics of the bedforms at their formation. Apart from studying the principal formation mechanism, the models have take into account various processes (three dimensional flows, sediment sorting, wave stirring, different tidal constituents, etc) to describe the characteristics of the bedforms at specific locations. Exploration of the finite amplitude regime have also been made with simplified models. Future model developments are needed to explore long-term dynamics.
2017-02-08T15:20:19ZFalqués Serra, AlbertRibas Prats, FrancescaA number of morphodynamic models have been developed to simulate the dynamics of large-scale bedform patterns on the continental shelf. Most of the models are based on linear stability analysis and, therefore, only describe the characteristics of the bedforms at their formation. Apart from studying the principal formation mechanism, the models have take into account various processes (three dimensional flows, sediment sorting, wave stirring, different tidal constituents, etc) to describe the characteristics of the bedforms at specific locations. Exploration of the finite amplitude regime have also been made with simplified models. Future model developments are needed to explore long-term dynamics.