Gerardo Ruiz Chavarria - Academia.edu (original) (raw)
Uploads
Papers by Gerardo Ruiz Chavarria
Cornell University - arXiv, Apr 1, 2014
We report laboratory experiments on surface waves generated in a uniform fluid layer whose bottom... more We report laboratory experiments on surface waves generated in a uniform fluid layer whose bottom undergoes a sudden upward motion. Simultaneous measurements of the free-surface deformation and the fluid velocity field are focused on the role of the bottom kinematics in wave generation. We observe that the fluid layer transfers bottom motion to the free surface as a temporal high-pass filter coupled with a spatial low-pass filter. Both filter effects are usually neglected in tsunami warning systems. Our results display good agreement with a prevailing linear theory without fitting parameter. Based on our experimental data, we provide a new theoretical approach for the rapid kinematics limit that is applicable even for non-flat bottoms: a key step since most approaches assume a uniform depth. This approach can be easily appended to tsunami simulations under arbitrary topography.
Journal of Fluid Mechanics, 2021
We describe and model experimental results on the dynamics of a ‘ludion’ – a neutrally buoyant bo... more We describe and model experimental results on the dynamics of a ‘ludion’ – a neutrally buoyant body – immersed in a layer of stably stratified salt water. By oscillating a piston inside a cylinder communicating with a narrow (in one of its horizontal dimensions) vessel containing the stably stratified layer of salt water, it is easy to periodically vary the hydrostatic pressure of the fluid. The ludion or Cartesian diver, initially positioned at its equilibrium height and free to move horizontally, can then oscillate vertically when forced by the pressure oscillations. Depending on the ratio of the forcing frequency to the Brunt–Väisälä frequency of the stratified fluid, the ludion can emit its own internal gravity waves that we measure by a classical particle image velocimetry technique. Our experimental results describe first the resonance of the vertical motions of the ludion when excited at different frequencies. A theoretical oscillator model is then derived taking into account...
Environmental Science and Engineering, 2011
In this work a numerical solution for the flow in a system of two basins connected by a channel i... more In this work a numerical solution for the flow in a system of two basins connected by a channel is presented. The flow rate is assumed to be time dependent. With this assumption we intend to model the effect of tides in coastal systems. Our results show the formation of a vortex dipole at the channel outlet. Evolution of dipole depends strongly on the period of flow rate, as already noted by previous works. Using the velocity field obtained with the numerical method we calculate trajectories of fluid particles and show that dipole has an effect of suction in the region it pass. On the other hand the process of vortex formation and further evolution are well described.
Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2015
We report laboratory experiments on surface waves generated in a uniform fluid layer whose bottom... more We report laboratory experiments on surface waves generated in a uniform fluid layer whose bottom undergoes an upward motion. Simultaneous measurements of the free-surface deformation and the fluid velocity field are focused on the role of the bottom kinematics (i.e. its spatio-temporal features) in wave generation. We observe that the fluid layer transfers bottom motion to the free surface as a temporal high-pass filter coupled with a spatial low-pass filter. Both filter effects are often neglected in tsunami warning systems, particularly in real-time forecast. Our results display good agreement with a prevailing linear theory without any parameter fitting. Based on our experimental findings, we provide a simple theoretical approach for modelling the rapid kinematics limit that is applicable even for initially non-flat bottoms: this may be a key step for more realistic varying bathymetry in tsunami scenarios.
Bulletin of the American Physical Society, 2016
Bulletin of the American Physical Society, 2012
Latin-American Journal of Physics Education, 2010
espanolLa ensenanza de temas asociados a la energia solar ha adquirido relevancia en los ultimos ... more espanolLa ensenanza de temas asociados a la energia solar ha adquirido relevancia en los ultimos anos a raiz del futuro agotamiento de combustibles fosiles y al problema del calentamiento global. En este trabajo se presenta un prototipo de concentrador solar construido con aluminio super pulido y basado en la optica de no enfoque. Entre las posibles aplicaciones se encuentran la construccion de estufas solares y de generadores en refrigeradores de absorcion de amoniaco en agua. Se estudian, tanto teorica como experimentalmente, los procesos de transferencia de calor que ocurren. En ausencia de fuentes de energia, los procesos de transferencia de calor modelan con la ley de enfriamiento de Newton. Sin embargo, cuando el sol aporta energia, el sistema se describe con un modelo mas complicado. Para poder conocer la evolucion de este sistema se miden dos variables termodinamicas (presion y temperatura). EnglishThe solar energy as a subject in the teaching of physics has a increasing int...
Minería y Geología, 2015
Se experimento con licor amoniacal con el fin de obtener los valores numericos de la presion de v... more Se experimento con licor amoniacal con el fin de obtener los valores numericos de la presion de vapor y establecer una relacion entre la caida de presion y la formacion de burbujas asociadas al fenomeno de la cavitacion en bombas centrifugas que trasiegan este fluido, en el cual estan presentes solidos disueltos y en suspension. La experimentacion se llevo a cabo en dos etapas en las que se obtuvo la presion de saturacion del licor amoniacal y la caida de presion cuando se induce la cavitacion en una bomba centrifuga. Se concluye que la presion de formacion de burbujas durante el trasiego del licor amoniacal a una concentracion de 27 % es de 45,6.103 Pa a 22,15 oC de temperatura de saturacion. Estos valores constituyen los limites inferiores de presion para que se produzca la cavitacion para una abertura de la valvula del 75 % en las bombas centrifugas que trasiegan licor amoniacal.
In this experimental and numerical study the process of spatial focusing of surface waves generat... more In this experimental and numerical study the process of spatial focusing of surface waves generated by a parabolic wavemaker is investigated. According to a focalization mechanism well-known in wave optics, the wave amplitude increases sharply near the cusp of Huygens, which may even lead to a local wave breaking. The theoretical scaling laws are verified in a laboratory model experiment and in 2D simulations. This mechanism could provide a generic explanation of the wave breaking in deep water in the vicinity of caustics. Mots clefs : deferlement, caustiques, ondes de surface
Bulletin of the American Physical Society, 2014
Bulletin of the American Physical Society, 2016
Bulletin of the American Physical Society, 2016
Con el fin de obtener el comportamiento dinamico de la presion de formacion de las burbujas y de ... more Con el fin de obtener el comportamiento dinamico de la presion de formacion de las burbujas y de su movimiento al inducir el fenomeno de la cavitacion en bombas centrifugas, se experimento con agua y licor amoniacal a dos concentraciones de amoniaco (27 % y 34 %). El comportamiento dinamico de las burbujas se soluciono numericamente con la aplicacion de la ecuacion de Rayleigh-Plesset, por medio de los radios de las burbujas y el tiempo de crecimiento de estas. Se concluye que cuando se induce la cavitacion, la presion de formacion de las burbujas a 22 oC es de 10,135.103 Pa para el agua; de 45,468.103 Pa para el licor amoniacal al 27 % de concentracion y de 69,951.103 Pa para una concentracion de 34 %. Los radios alcanzados por las burbujas en el licor amoniacal son del orden de 30 a 120 veces su radio inicial, mientras que para las burbujas formadas en el agua son del orden de 15 veces solamente.
This article exposes the effect bubbles implosion causes on buckets on the liquor from carbonate-... more This article exposes the effect bubbles implosion causes on buckets on the liquor from carbonate-ammonia leaching (mixture of water, ammonia and particles in suspension) of ferronickel lateritic ores. Based on the previous results that establish a relationship between the bubbles’ size and the ammonia concentration of the liquor, the microstructure of a Hastelloy C 276 steel blade affected by cavitation was analyzed. It was also obtained that affectations are smaller in the initial area of the bucket than the distal parts, where complete perforations can be produced in the metal, what is associated to the fact that bubbles develop a great size at a concentration of 34% of ammonia in the liquor and implode at the exit of the bucket producing more intense pressure waves than those generated by the bubbles formed at 27% and that implode in the initial zone. It is concluded that the microstructural changes in the bucket material are closely related to the concentration of ammonia in the...
Cornell University - arXiv, Apr 1, 2014
We report laboratory experiments on surface waves generated in a uniform fluid layer whose bottom... more We report laboratory experiments on surface waves generated in a uniform fluid layer whose bottom undergoes a sudden upward motion. Simultaneous measurements of the free-surface deformation and the fluid velocity field are focused on the role of the bottom kinematics in wave generation. We observe that the fluid layer transfers bottom motion to the free surface as a temporal high-pass filter coupled with a spatial low-pass filter. Both filter effects are usually neglected in tsunami warning systems. Our results display good agreement with a prevailing linear theory without fitting parameter. Based on our experimental data, we provide a new theoretical approach for the rapid kinematics limit that is applicable even for non-flat bottoms: a key step since most approaches assume a uniform depth. This approach can be easily appended to tsunami simulations under arbitrary topography.
Journal of Fluid Mechanics, 2021
We describe and model experimental results on the dynamics of a ‘ludion’ – a neutrally buoyant bo... more We describe and model experimental results on the dynamics of a ‘ludion’ – a neutrally buoyant body – immersed in a layer of stably stratified salt water. By oscillating a piston inside a cylinder communicating with a narrow (in one of its horizontal dimensions) vessel containing the stably stratified layer of salt water, it is easy to periodically vary the hydrostatic pressure of the fluid. The ludion or Cartesian diver, initially positioned at its equilibrium height and free to move horizontally, can then oscillate vertically when forced by the pressure oscillations. Depending on the ratio of the forcing frequency to the Brunt–Väisälä frequency of the stratified fluid, the ludion can emit its own internal gravity waves that we measure by a classical particle image velocimetry technique. Our experimental results describe first the resonance of the vertical motions of the ludion when excited at different frequencies. A theoretical oscillator model is then derived taking into account...
Environmental Science and Engineering, 2011
In this work a numerical solution for the flow in a system of two basins connected by a channel i... more In this work a numerical solution for the flow in a system of two basins connected by a channel is presented. The flow rate is assumed to be time dependent. With this assumption we intend to model the effect of tides in coastal systems. Our results show the formation of a vortex dipole at the channel outlet. Evolution of dipole depends strongly on the period of flow rate, as already noted by previous works. Using the velocity field obtained with the numerical method we calculate trajectories of fluid particles and show that dipole has an effect of suction in the region it pass. On the other hand the process of vortex formation and further evolution are well described.
Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2015
We report laboratory experiments on surface waves generated in a uniform fluid layer whose bottom... more We report laboratory experiments on surface waves generated in a uniform fluid layer whose bottom undergoes an upward motion. Simultaneous measurements of the free-surface deformation and the fluid velocity field are focused on the role of the bottom kinematics (i.e. its spatio-temporal features) in wave generation. We observe that the fluid layer transfers bottom motion to the free surface as a temporal high-pass filter coupled with a spatial low-pass filter. Both filter effects are often neglected in tsunami warning systems, particularly in real-time forecast. Our results display good agreement with a prevailing linear theory without any parameter fitting. Based on our experimental findings, we provide a simple theoretical approach for modelling the rapid kinematics limit that is applicable even for initially non-flat bottoms: this may be a key step for more realistic varying bathymetry in tsunami scenarios.
Bulletin of the American Physical Society, 2016
Bulletin of the American Physical Society, 2012
Latin-American Journal of Physics Education, 2010
espanolLa ensenanza de temas asociados a la energia solar ha adquirido relevancia en los ultimos ... more espanolLa ensenanza de temas asociados a la energia solar ha adquirido relevancia en los ultimos anos a raiz del futuro agotamiento de combustibles fosiles y al problema del calentamiento global. En este trabajo se presenta un prototipo de concentrador solar construido con aluminio super pulido y basado en la optica de no enfoque. Entre las posibles aplicaciones se encuentran la construccion de estufas solares y de generadores en refrigeradores de absorcion de amoniaco en agua. Se estudian, tanto teorica como experimentalmente, los procesos de transferencia de calor que ocurren. En ausencia de fuentes de energia, los procesos de transferencia de calor modelan con la ley de enfriamiento de Newton. Sin embargo, cuando el sol aporta energia, el sistema se describe con un modelo mas complicado. Para poder conocer la evolucion de este sistema se miden dos variables termodinamicas (presion y temperatura). EnglishThe solar energy as a subject in the teaching of physics has a increasing int...
Minería y Geología, 2015
Se experimento con licor amoniacal con el fin de obtener los valores numericos de la presion de v... more Se experimento con licor amoniacal con el fin de obtener los valores numericos de la presion de vapor y establecer una relacion entre la caida de presion y la formacion de burbujas asociadas al fenomeno de la cavitacion en bombas centrifugas que trasiegan este fluido, en el cual estan presentes solidos disueltos y en suspension. La experimentacion se llevo a cabo en dos etapas en las que se obtuvo la presion de saturacion del licor amoniacal y la caida de presion cuando se induce la cavitacion en una bomba centrifuga. Se concluye que la presion de formacion de burbujas durante el trasiego del licor amoniacal a una concentracion de 27 % es de 45,6.103 Pa a 22,15 oC de temperatura de saturacion. Estos valores constituyen los limites inferiores de presion para que se produzca la cavitacion para una abertura de la valvula del 75 % en las bombas centrifugas que trasiegan licor amoniacal.
In this experimental and numerical study the process of spatial focusing of surface waves generat... more In this experimental and numerical study the process of spatial focusing of surface waves generated by a parabolic wavemaker is investigated. According to a focalization mechanism well-known in wave optics, the wave amplitude increases sharply near the cusp of Huygens, which may even lead to a local wave breaking. The theoretical scaling laws are verified in a laboratory model experiment and in 2D simulations. This mechanism could provide a generic explanation of the wave breaking in deep water in the vicinity of caustics. Mots clefs : deferlement, caustiques, ondes de surface
Bulletin of the American Physical Society, 2014
Bulletin of the American Physical Society, 2016
Bulletin of the American Physical Society, 2016
Con el fin de obtener el comportamiento dinamico de la presion de formacion de las burbujas y de ... more Con el fin de obtener el comportamiento dinamico de la presion de formacion de las burbujas y de su movimiento al inducir el fenomeno de la cavitacion en bombas centrifugas, se experimento con agua y licor amoniacal a dos concentraciones de amoniaco (27 % y 34 %). El comportamiento dinamico de las burbujas se soluciono numericamente con la aplicacion de la ecuacion de Rayleigh-Plesset, por medio de los radios de las burbujas y el tiempo de crecimiento de estas. Se concluye que cuando se induce la cavitacion, la presion de formacion de las burbujas a 22 oC es de 10,135.103 Pa para el agua; de 45,468.103 Pa para el licor amoniacal al 27 % de concentracion y de 69,951.103 Pa para una concentracion de 34 %. Los radios alcanzados por las burbujas en el licor amoniacal son del orden de 30 a 120 veces su radio inicial, mientras que para las burbujas formadas en el agua son del orden de 15 veces solamente.
This article exposes the effect bubbles implosion causes on buckets on the liquor from carbonate-... more This article exposes the effect bubbles implosion causes on buckets on the liquor from carbonate-ammonia leaching (mixture of water, ammonia and particles in suspension) of ferronickel lateritic ores. Based on the previous results that establish a relationship between the bubbles’ size and the ammonia concentration of the liquor, the microstructure of a Hastelloy C 276 steel blade affected by cavitation was analyzed. It was also obtained that affectations are smaller in the initial area of the bucket than the distal parts, where complete perforations can be produced in the metal, what is associated to the fact that bubbles develop a great size at a concentration of 34% of ammonia in the liquor and implode at the exit of the bucket producing more intense pressure waves than those generated by the bubbles formed at 27% and that implode in the initial zone. It is concluded that the microstructural changes in the bucket material are closely related to the concentration of ammonia in the...