Anales AFA最新文献

{"title":"DYNAMIC CLASSIFICATION OF BELTRAMI FLOWS","authors":"R. González","doi":"10.31527/analesafa.2021.33.fluidos.1","DOIUrl":"https://doi.org/10.31527/analesafa.2021.33.fluidos.1","url":null,"abstract":"We study four configurations of Beltrami flows (BFs) defined as ∇ × v = ±γ ±v, where γ > 0 is an eigenvalue and which have a progressive rotating wave dynamics (PRWs) that satisfies the dynamic property (DP) [1], which allows us to classify them on the basis of the eigenvalues that result in each configuration. The first configuration corresponds to an infinite volume domain without contours. The classifier eigenvalue is γ ±ph = 2/ vph± where k is the modulus of the wave vector that forms an angle θ with the rotation axis. The result is a finite-amplitude, transverse, dispersive, circularly polarised, planar PRWs with a continuous spectrum. The second configuration has the same domain as configuration one. The classifying eigenvalue is γ ±ph = 2/ vph± with vph being the phase velocity, with vph+ < 0 and vph− > 0. They are axi-symmetric or non-axi-symmetric along the axis of rotation, of finite amplitude, non-dispersive and with motion between concentric cylinders at which the radial velocity equals zero. In the third configuration the fluid is confined in an infinite cylinder. The classifying eigenvalue is again γ ±ph but it results discretized by the boundary conditions on the cylinder wall. Classification is exemplified for vph+ = −0.1 and three rotating modes with m = 0, m = 1 y m = 2. These are finite amplitude dispersive PRWs. The fourth configuration consists of a rotational-translational flow, characterized by the Rossby number R0 (=U/a Ω) which is an intake flow to a semi-infinite cylinder. The classifying eigenvalue is γ ±ph with vph± = ∓R0. These are PRWs, of the same type as in the infinite cylinder, but dependent on R0. It is shown that these waves exist only in the interval R0 ∈ (0,0.642]. Where for R0 = 0.642 one has only the mode with m = 1 and as R0 decreases the modes m = 0 and m ≥ 2 arise successively. It is observed that, for the same R0, waves of the same sign of frequency do not exchange energy. For each configuration the possibilities and conditions of resonant triadic interactions are analyzed.","PeriodicalId":41478,"journal":{"name":"Anales AFA","volume":"15 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2022-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83409142","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"IMPACT OF DESIGN PARAMETERS ON THE NATURAL VENTILATION OF A FAMILY HOUSE ATTIC FROM SANTA FE (ARGENTINA)","authors":"M. Berli, A. Brondino, J. Di Paolo","doi":"10.31527/analesafa.2022.fluidos.46","DOIUrl":"https://doi.org/10.31527/analesafa.2022.fluidos.46","url":null,"abstract":"The roof of a family home introduces important amounts of heat into the house. In Santa Fe city (Argentina), the attic of social family houses is not designed with thermal optimization purposes. In this work, a low Reynolds number k-e turbulent model is computationally implemented to show that a proper selection of constructive parameters of a vented attic leads to a great reduction of the heat transferred from the roof to the ceiling. The main physical consequence of a vented attic is the existence of a convective flow barrier close to the roof that carries important amounts of heat from the attic out to the environment. It is shown that the heat transferred through the ceiling to the interior of the house can be reduced in more than 70 % for summer conditions. Roof pitch and attic volume are also explored.","PeriodicalId":41478,"journal":{"name":"Anales AFA","volume":"5 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2022-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86841593","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"NUMERICAL ANALYSIS OF VISCOELASTOHYDRODYNAMIC LUBRICATION IN KNEE PROSTHESIS WITH NON-NEWTONIAN FLUID","authors":"L.E. Robledo Blasco, B. Weiss, M. Berli, J. Di Paolo","doi":"10.31527/analesafa.2022.fluidos.57","DOIUrl":"https://doi.org/10.31527/analesafa.2022.fluidos.57","url":null,"abstract":"In this work, a computational model of thin film lubrication applied to a knee prosthesis was designed in order to make a comparison between three constitutive models, i.e. a power law, the Carreau-Yasuda model and the Cross model. The equivalent model of the knee prosthesis was modeled as a rigid cylinder on a deformable plane. The mechanical behavior of the deformable component representing the tibial base was assumed as a viscoelastic Standard Linear Solid(SLS). The governing equations were solved simultaneously with the determination of a free-moving boundary by implementing it in COMSOL Multiphysics software. The results obtained showed that the Cross model presents the highest shear rate value, the lowest film thickness and the dynamic viscosity with less variation along the lubrication channel, reaching a minimum viscosity value of 0.02 Pa.s. The Carreau-Yasuda model presents the highest value of friction coefficient, being 21.5 % higher than for the Power Law model and 3.67 % higher than the Cross model.","PeriodicalId":41478,"journal":{"name":"Anales AFA","volume":"21 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2022-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74163444","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"FLOW CALCULATION IN A STANDING TIDAL WAVE ESTUARY","authors":"L. P. Thomas, B. M. Marino","doi":"10.31527/analesafa.2022.fluidos.16","DOIUrl":"https://doi.org/10.31527/analesafa.2022.fluidos.16","url":null,"abstract":"The hydrodynamic behaviour of the micro tidal and 13.9-km-long Quequén Grande River estuary (Buenos Aires, Argentina), in which the tide behaves as a standing wave, is studied analytically and numerically. Results provided by the SisBaHiA program are validated with the measurements performed with two acoustic Doppler current profilers in stations located at 1.4, 2.9, 7.5 and 11.3 km from the estuary mouth. The numerical model reproduces the differences between the measured water column height and the equilibrium height in each station. In particular, the numerical values of the flow and tidal height are analyzed during a spring tide cycle by considering nine times corresponding to the maximum, minimum, and close to the equilibrium levels. The time variations in the free surface height and flow along the estuary are explained successfully by an analytical model based on the Saint Venant one-dimensional equations as a function of the river discharge and the tidal height in the estuary mouth and the bed and friction slopes.","PeriodicalId":41478,"journal":{"name":"Anales AFA","volume":"429 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2022-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76636847","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"OSCILLATING BUBBLES RISING IN A DOUBLY CONFINED CELL","authors":"L. Pavlov, M. D'Angelo, M. Cachile, V. Roig, P. Ern","doi":"10.31527/analesafa.2022.fluidos.66","DOIUrl":"https://doi.org/10.31527/analesafa.2022.fluidos.66","url":null,"abstract":"The motion of bubbles rising in confined geometries has gained interest due to its applications in mixing and mass transfer processes, ranging from bubble column reactors in the chemical industry to solar photobioreactors for algae cultivation. In this work we performed an experimental investigation of the behavior of air bubbles freely rising at high Reynolds numbers in a planar thin-gap cell of thicknessh=2.8 mm filled with distilled water. The in-plane width of the cell W is varied from 2.4 cm to 21 cm. We focus on the influence of lateral confinement on the motion of bubbles in the regimes with regular path and shape oscillations of large amplitude, that occur for the size range 0.6 cm<d<1.2cm. In addition, a rise regime that consists of a vertical rise path with regular shape oscillations, that does not appear in the laterally unconfined case, is uncovered. In the presence of lateral walls, the mean rise velocity of the bubble Vb becomes lower than the velocity of a laterally unconfined bubble of the same size beyond a critical bubble diameterdcVthat decreases as the confinement increases(i.e. as W decreases). The influence of the lateral confinement on the bubble mean shape can be determined from the change in the mean aspect ratio χ of the ellipse that best fits the bubble contour at each instant. It is observed that bubbles become closer to circular (χcloser to 1) as the confinement increases. The departure from the values of χ of the laterally unconfined case occur at a critical diameter dcχ that is lower for greater confinement and also greater than dcV for each confinement, thus indicating that the effect of the lateral confinement is seen earlier (i.e. on smaller bubbles) on the velocity than on the aspect ratio. Assuming that the wall effect is related to the strength of the downward flow generated by the bubble, we introduce the mean flow velocity in the space let free for the liquid between the walls and the bubble, Uf, that can be estimated by mass conservation as Uf=dVb/(W−d). We further introduce the relative velocity between the bubble and the downward fluid in its vicinity Urel=Vb+Uf=Vb/ξ, whereξ=1−d/Wis the confinement ratio of the bubble. We found that, for a given bubble size in the oscillatory regime, Urel is approximately constant for all the studied values of W, and matches closely the value in the absence of lateral confinement. This provides an estimation, at leading order, of the bubble velocity that generalizes the expression proposed by Filella et al. (JFM, 2015) and accounts for the additional drag experienced by the bubble due to the lateral walls. We then show that, for givendandξ, the frequency and amplitudes of the oscillatory motion can be predicted using the characteristic length and velocity scalesdandUrel.","PeriodicalId":41478,"journal":{"name":"Anales AFA","volume":"18 3 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2022-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91243339","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"WATER TREATMENT WITH A PULSED CORONA DISCHARGE","authors":"M. Ferreyra, B. Fina, N. Milardovich, J. Chamorro, B. Santamaria, L. Prevosto","doi":"10.31527/analesafa.2022.fluidos.11","DOIUrl":"https://doi.org/10.31527/analesafa.2022.fluidos.11","url":null,"abstract":"One of the fastest growing technological applications in recent years in the area of non-thermal plasmas is the treatment of water with discharges in (and in contact with) liquids. Reactive chemical species are generated in the plasma in the gas phase and enter the liquid by diffusion or are generated at the gas-liquid interface, thus changing its physicochemical properties, without the addition of external chemical compounds. Depending on the form of application of the plasma, well-differentiated effects can be achieved: on the one hand, the purification of water through the degradation of organic pollutants, and on the other, its activation, through long-lived reactive species, for later use in seeds and food treatments. In this work, the first results obtained in the water treated with a pulsed corona discharge under different exposure times are reported. In particular, measurement results of indigo carmine degradation; electric conductivity; pH; aqueous concentrations of reactive species, such as nitrate, nitrite, hydrogen peroxide and ozone, are reported. The results are discussed and compared with published data.","PeriodicalId":41478,"journal":{"name":"Anales AFA","volume":"78 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2022-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91238722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"STUDY OF VON KÁRMÁN INSTABILITY RESULTING FROM A BINARY CYLINDER SYSTEM","authors":"J. Rozas, R. Hernández","doi":"10.31527/analesafa.2022.fluidos.31","DOIUrl":"https://doi.org/10.31527/analesafa.2022.fluidos.31","url":null,"abstract":"Experimental results are presented of the temporal evolution of the wake associated with von Kármán, instability produced by a system of two vertical cylinders of different diameters (binary cylindrical system) facing a uniform airflow. The goal is to study the influence of the binary system on the linear stability of the wake at moderate Reynolds numbers, as well as the vortex emission. From the measurements of the velocity profiles we were able to analyze the wake’s dynamic behaviour in both the subcritical and critical ranges. Furthermore, it was possible to determine the frequency content of the vortex emission of the system, finding a coupling (lock-in) in the wake of both cylinders at the onset of the von Kármán instability. This coupling is developed, even, in the condition of greatest distance between the wakes(α=90◦). The non-linear condition of the wake is reflected in the power spectrum (PSD) of the velocity time series, presenting additional frequency modes to the fundamental vortex shedding frequency of each cylinder.","PeriodicalId":41478,"journal":{"name":"Anales AFA","volume":"1 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2022-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88849892","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"INFILTRATION IN A COMPLEX BUILDING","authors":"N. Muñoz, L. P. Thomas, B. M. Marino","doi":"10.31527/analesafa.2022.fluidos.71","DOIUrl":"https://doi.org/10.31527/analesafa.2022.fluidos.71","url":null,"abstract":"The air infiltration through building envelope mainly depends on the doors and windows tightness considered by means of the corresponding effective leakage areas and the pressure difference between the building exterior and interior. Although the standards provide simple methods to estimate the parameters that control the air movement, significant differences in the volumetric flow of fresh air are observed between the standardized and the most accurate traditional methods. Our aim is to evaluate the infiltration in a two-storey building with a large central atrium during the typical day in January by considering all the relevant parameters. The analytical result is incorporated to the numerical simulation with EnergyPlus to determine the internal temperature evolution that is sensitive to the air intake. Simulation results are compared with in-situ measurements. It is found that the air infiltration rate calculated from the standardized procedure only enables the internal temperature evolution to be reproduced with a substantial adjustment of the design air infiltration rate. The methodology developed is useful to calculate the infiltration in buildings under actual use conditions and assess the air leakage when measurements are not available.","PeriodicalId":41478,"journal":{"name":"Anales AFA","volume":"13 1 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2022-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77844352","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"COMPUTATIONAL MODEL AND EXPERIMENTAL VERIFICATION OF IN DEPTH DOSE PERFORMANCE TO GENERATE SPREAD OUT BRAGG PEAKS (SOBP) FOR INTRACRANIAL IRRADIATIONS","authors":"C. Salinas Domján, D. Franco, M. Valente","doi":"10.31527/analesafa.2022.33.2.54","DOIUrl":"https://doi.org/10.31527/analesafa.2022.33.2.54","url":null,"abstract":"This work reports on a computational modeling methodology through Monte Carlo simulations based on the FLUKAcode to describe the physical processes in proton therapy irradiations. The corresponding validation by comparison with experimental data is shown and the SOBP generation procedure applied to intracranial irradiations is described. Promising performance has been achieved in terms of the good agreements between experimental and simulation data, while the SOBP generation procedure has proved to attain acceptable dose concentration and uniformity, this constituting a promising issue for local control and protection of areas at risk for intracranial applications.","PeriodicalId":41478,"journal":{"name":"Anales AFA","volume":"1 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2022-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78239971","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"\"ME TIRÉ POR VOS\" A PHYSICAL ANALYSIS OF CHARLY GARCÍA’S JUMP","authors":"M. Echiburu, R. Parra","doi":"10.31527/analesafa.2022.33.2.36","DOIUrl":"https://doi.org/10.31527/analesafa.2022.33.2.36","url":null,"abstract":"In the present work, the famous jump of Charly García is studied, thus proposing to contextualize a situation of a public nature in the field of physics. Video analysis was used, which allowed to compare classical kinematics models with experimental data from the fall, thereby determining the artist’s position and speed while moving in the air. The movement in the water was subsequently analyzed, obtaining different possibilities according to the variations of the parameters under study. This proposal reaffirms the use of this type of problem as a successful and highly versatile pedagogical tool for use in the classroom","PeriodicalId":41478,"journal":{"name":"Anales AFA","volume":"69 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2022-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80365168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}