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117 results on '"de Barros, Felipe P. J."'

3. Pictures of Blockscale Transport: Effective versus Ensemble Dispersion and Its Uncertainty

Author

de Barros, Felipe P. J. and Dentz, Marco

Subjects
Physics - Fluid Dynamics
Abstract

Using a Lagrangian framework, we discuss different conceptualizations of the blockscale dispersion tensor. We distinguish effective and ensemble blockscale dispersion, which measure the impact of subscale velocity fluctuations on solute dispersion. Ensemble dispersion quantifies subscale velocity fluctuations between realizations, which overestimates the actual velocity variability. Effective dispersion on the other hand quantifies the actual blockscale velocity variability and thus reflects the impact of subscale velocity fluctuations on mixing and spreading. Based on these concepts, we quantify the impact of subscale velocity fluctuations on solute particle spreading and determine the governing equations for the coarse-grained concentration distributions. We develop analytical and semi-analytical expressions for the average and variance of the blockscale dispersion tensor in 3D flow fields as a function of the structural parameters characterizing the subsurface. Our results illustrate the relevance of the blockscale, the initial scale of the solute body and local-scale dispersion in controlling the uncertainty of the plume's dispersive behavior. The analysis performed in this work has implications in numerical modeling (i.e. grid design) and allows to quantify the uncertainty of the blockscale dispersion tensor.

Published
2016
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5. The Lagrangian Deformation Structure of Three-Dimensional Steady Flow

Author

Lester, Daniel R., Dentz, Marco, Borgne, Tanguy Le, and de Barros, Felipe P. J.

Subjects
Physics - Fluid Dynamics
Abstract

Fluid deformation and strain history are central to wide range of fluid mechanical phenomena ranging from fluid mixing and particle transport to stress development in complex fluids and the formation of Lagrangian coherent structures (LCSs). To understand and model these processes it is necessary to quantify Lagrangian deformation in terms of Eulerian flow properties, currently an open problem. To elucidate this link we develop a Protean (streamline) coordinate transform for steady three-dimensional (3D) flows which renders both the velocity gradient and deformation gradient upper triangular. This frame not only simplifies computation of fluid deformation metrics such as finite-time Lyapunov exponents (FTLEs) and elucidates the deformation structure of the flow, but moreover explicitly recovers kinematic and topological constraints upon deformation such as those related to helicity density and the Poincar\'{e}-Bendixson theorem. We apply this transform to several classes of steady 3D flow, including helical and non-helical, compressible and incompressible flows, and find random flows exhibit remarkably simple (Gaussian) deformation structure, and so are fully characterised in terms of a small number of parameters. As such this technique provides the basis for the development of stochastic models of fluid deformation in random flows which adhere to the kinematic constraints inherent to various flow classes., Comment: 18 pages

Published
2016

6. Fluid Stretching as a Levy Process

Author

Dentz, Marco, Lester, Daniel R., Borgne, Tanguy Le, and de Barros, Felipe P. J.

Subjects
Physics - Fluid Dynamics, 76S05, 60G51
Abstract

We study the relation between flow structure and fluid deformation in steady two-dimensional random flows. Beyond the linear (shear flow) and exponential (chaotic flow) elongation paradigms, we find a broad spectrum of stretching behaviors, ranging from sub- to superlinear, which are dominated by intermittent shear events. We analyze these behaviors from first principles, which uncovers stretching as a result of the non-linear coupling between Lagrangian shear deformation and velocity fluctuations along streamlines. We derive explicit expressions for Lagrangian deformation and demonstrate that stretching obeys a coupled continous time random walk, which for broad distributions of flow velocities describes a L\'evy walk for elongation. The derived model provides a direct link between the flow and deformation statistics, and a natural way to quantify the impact of intermittent shear events on the stretching behavior, which can have strong anomalous diffusive character., Comment: 12 pages, 5 figures

Published
2016

20. Estimating Dispersion Coefficient in Flow Through Heterogeneous Porous Media by a Deep Convolutional Neural Network.

Author

Kamrava, Serveh, Im, Jinwoo, de Barros, Felipe P. J., and Sahimi, Muhammad

Subjects
CONVOLUTIONAL neural networks, POROUS materials, FLOW coefficient, DISPERSION (Chemistry), GEOLOGICAL formations
Abstract

Estimating the longitudinal dispersion coefficient DL in flow through heterogeneous porous media is paramount to many problems in geological formations. Moreover, although it is well‐known that DL is sensitive to the morphology of such formations, it has been very difficult to establish a firm link between the two. We describe a novel deep convolutional neural network (DCNN) for estimating DL. The inputs for training of the network are a large and diverse set of data consisting of three‐dimensional images of porous media, as well as their porosity, and the associated DL values computed by random‐walk particle‐tracking (RWPT) simulations. The trained network predicts DL very rapidly, and its predictions are in excellent agreement with the data not used in the training. Thus, a combination of the DCNN and RWPT simulation provides a powerful tool for studying many flow‐related phenomena in geological formations, and estimating their properties. Plain Language Summary: Measuring or computing the dispersion coefficient DL in flow through porous media, a fundamental characteristic of transport in geological formations and risk analysis, is a time‐consuming endeaver. Moreover, although DL is sensitive to the morphology of a pore space, a direct link between the two has been missing. We proposed a deep convolutional neural network for predicting DL, using 3D images of porous media and their porosities. The accuracy of the predictions for the actual data indicates that the ability of the network for estimating the important flow and transport properties of porous media for new input data. The present work was at the core scale, on the order of the physical sizes of the sandstones used in our study. The same approach may be used at the eld scale. In that case, one generates the input data by following the same procedure, except that the data should be generated for models in which the permeability and porosity of the formation vary spatially, and represent correlated fields. Work in this direction is in progress. Key Points: Dispersion coefficientConvolutional neural networkFlow through porous media [ABSTRACT FROM AUTHOR]

Published
2021
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22. Twenty-three unsolved problems in hydrology (UPH) – a community perspective

Author

Blöschl, Günter, primary, Bierkens, Marc F.P., additional, Chambel, Antonio, additional, Cudennec, Christophe, additional, Destouni, Georgia, additional, Fiori, Aldo, additional, Kirchner, James W., additional, McDonnell, Jeffrey J., additional, Savenije, Hubert H.G., additional, Sivapalan, Murugesu, additional, Stumpp, Christine, additional, Toth, Elena, additional, Volpi, Elena, additional, Carr, Gemma, additional, Lupton, Claire, additional, Salinas, Josè, additional, Széles, Borbála, additional, Viglione, Alberto, additional, Aksoy, Hafzullah, additional, Allen, Scott T., additional, Amin, Anam, additional, Andréassian, Vazken, additional, Arheimer, Berit, additional, Aryal, Santosh K., additional, Baker, Victor, additional, Bardsley, Earl, additional, Barendrecht, Marlies H., additional, Bartosova, Alena, additional, Batelaan, Okke, additional, Berghuijs, Wouter R., additional, Beven, Keith, additional, Blume, Theresa, additional, Bogaard, Thom, additional, Borges de Amorim, Pablo, additional, Böttcher, Michael E., additional, Boulet, Gilles, additional, Breinl, Korbinian, additional, Brilly, Mitja, additional, Brocca, Luca, additional, Buytaert, Wouter, additional, Castellarin, Attilio, additional, Castelletti, Andrea, additional, Chen, Xiaohong, additional, Chen, Yangbo, additional, Chen, Yuanfang, additional, Chifflard, Peter, additional, Claps, Pierluigi, additional, Clark, Martyn P., additional, Collins, Adrian L., additional, Croke, Barry, additional, Dathe, Annette, additional, David, Paula C., additional, de Barros, Felipe P. J., additional, de Rooij, Gerrit, additional, Di Baldassarre, Giuliano, additional, Driscoll, Jessica M., additional, Duethmann, Doris, additional, Dwivedi, Ravindra, additional, Eris, Ebru, additional, Farmer, William H., additional, Feiccabrino, James, additional, Ferguson, Grant, additional, Ferrari, Ennio, additional, Ferraris, Stefano, additional, Fersch, Benjamin, additional, Finger, David, additional, Foglia, Laura, additional, Fowler, Keirnan, additional, Gartsman, Boris, additional, Gascoin, Simon, additional, Gaume, Eric, additional, Gelfan, Alexander, additional, Geris, Josie, additional, Gharari, Shervan, additional, Gleeson, Tom, additional, Glendell, Miriam, additional, Gonzalez Bevacqua, Alena, additional, González-Dugo, María P., additional, Grimaldi, Salvatore, additional, Gupta, A. B., additional, Guse, Björn, additional, Han, Dawei, additional, Hannah, David, additional, Harpold, Adrian, additional, Haun, Stefan, additional, Heal, Kate, additional, Helfricht, Kay, additional, Herrnegger, Mathew, additional, Hipsey, Matthew, additional, Hlaváčiková, Hana, additional, Hohmann, Clara, additional, Holko, Ladislav, additional, Hopkinson, Christopher, additional, Hrachowitz, Markus, additional, Illangasekare, Tissa H., additional, Inam, Azhar, additional, Innocente, Camyla, additional, Istanbulluoglu, Erkan, additional, Jarihani, Ben, additional, Kalantari, Zahra, additional, Kalvans, Andis, additional, Khanal, Sonu, additional, Khatami, Sina, additional, Kiesel, Jens, additional, Kirkby, Mike, additional, Knoben, Wouter, additional, Kochanek, Krzysztof, additional, Kohnová, Silvia, additional, Kolechkina, Alla, additional, Krause, Stefan, additional, Kreamer, David, additional, Kreibich, Heidi, additional, Kunstmann, Harald, additional, Lange, Holger, additional, Liberato, Margarida L. R., additional, Lindquist, Eric, additional, Link, Timothy, additional, Liu, Junguo, additional, Loucks, Daniel Peter, additional, Luce, Charles, additional, Mahé, Gil, additional, Makarieva, Olga, additional, Malard, Julien, additional, Mashtayeva, Shamshagul, additional, Maskey, Shreedhar, additional, Mas-Pla, Josep, additional, Mavrova-Guirguinova, Maria, additional, Mazzoleni, Maurizio, additional, Mernild, Sebastian, additional, Misstear, Bruce Dudley, additional, Montanari, Alberto, additional, Müller-Thomy, Hannes, additional, Nabizadeh, Alireza, additional, Nardi, Fernando, additional, Neale, Christopher, additional, Nesterova, Nataliia, additional, Nurtaev, Bakhram, additional, Odongo, Vincent O., additional, Panda, Subhabrata, additional, Pande, Saket, additional, Pang, Zhonghe, additional, Papacharalampous, Georgia, additional, Perrin, Charles, additional, Pfister, Laurent, additional, Pimentel, Rafael, additional, Polo, María J., additional, Post, David, additional, Prieto Sierra, Cristina, additional, Ramos, Maria-Helena, additional, Renner, Maik, additional, Reynolds, José Eduardo, additional, Ridolfi, Elena, additional, Rigon, Riccardo, additional, Riva, Monica, additional, Robertson, David E., additional, Rosso, Renzo, additional, Roy, Tirthankar, additional, Sá, João H.M., additional, Salvadori, Gianfausto, additional, Sandells, Mel, additional, Schaefli, Bettina, additional, Schumann, Andreas, additional, Scolobig, Anna, additional, Seibert, Jan, additional, Servat, Eric, additional, Shafiei, Mojtaba, additional, Sharma, Ashish, additional, Sidibe, Moussa, additional, Sidle, Roy C., additional, Skaugen, Thomas, additional, Smith, Hugh, additional, Spiessl, Sabine M., additional, Stein, Lina, additional, Steinsland, Ingelin, additional, Strasser, Ulrich, additional, Su, Bob, additional, Szolgay, Jan, additional, Tarboton, David, additional, Tauro, Flavia, additional, Thirel, Guillaume, additional, Tian, Fuqiang, additional, Tong, Rui, additional, Tussupova, Kamshat, additional, Tyralis, Hristos, additional, Uijlenhoet, Remko, additional, van Beek, Rens, additional, van der Ent, Ruud J., additional, van der Ploeg, Martine, additional, Van Loon, Anne F., additional, van Meerveld, Ilja, additional, van Nooijen, Ronald, additional, van Oel, Pieter R., additional, Vidal, Jean-Philippe, additional, von Freyberg, Jana, additional, Vorogushyn, Sergiy, additional, Wachniew, Przemyslaw, additional, Wade, Andrew J., additional, Ward, Philip, additional, Westerberg, Ida K., additional, White, Christopher, additional, Wood, Eric F., additional, Woods, Ross, additional, Xu, Zongxue, additional, Yilmaz, Koray K., additional, and Zhang, Yongqiang, additional

Published
2019
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23. Radial solute transport in highly heterogeneous aquifers: Modeling and experimental comparison

Author

Di Dato, Mariaines, Fiori, Aldo, de Barros, Felipe P. J., Bellin, Alberto, Di Dato, Mariaine, Fiori, Aldo, de Barros, Felipe P. J., and Bellin, Alberto

Subjects
radial flow, ergodicity, groundwater transport, highly heterogeneous aquifer, travel time approach, Water Science and Technology
Abstract

We analyze solute transport in a radially converging 3-D flow field in a porous medium with spatially heterogeneous hydraulic conductivity (K). The aim of the paper is to analyze the impact of heterogeneity and the mode of injection on BreakThrough Curves (BTCs) detected at a well pumping a contaminated aquifer. The aquifer is conceptualized as an ensemble of blocks of uniform but contrasting K and the analysis makes use of the travel time approach. Despite the approximations introduced, the model reproduces a laboratory experiment without calibration of transport parameters. Our results also show excellent agreement with numerical simulations for different levels of heterogeneity. We focus on the impact on the BTC of both heterogeneity in K and solute release conditions. It is shown that the injection mode matters, and the differences in the BTCs between uniform and flux-proportional injection increase with the heterogeneity of the K-field. Furthermore, we study the effect of heterogeneity and mode of injection on early and late arrivals at the well.

Published
2017
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24. Twenty-three unsolved problems in hydrology (UPH) - a community perspective

Author

Bloeschl, Gunter, Bierkens, Marc F. P., Chambel, Antonio, Cudennec, Christophe, Destouni, Georgia, Fiori, Aldo, Kirchner, James W., McDonnell, Jeffrey J., Savenije, Hubert H. G., Sivapalan, Murugesu, Stumpp, Christine, Toth, Elena, Volpi, Elena, Carr, Gemma, Lupton, Claire, Salinas, Jose, Szeles, Borbala, Viglione, Alberto, Aksoy, Hafzullah, Allen, Scott T., Amin, Anam, Andreassian, Vazken, Arheimer, Berit, Aryal, Santosh K., Baker, Victor, Bardsley, Earl, Barendrecht, Marlies H., Bartosova, Alena, Batelaan, Okke, Berghuijs, Wouter R., Beven, Keith, Blume, Theresa, Bogaard, Thom, de Amorim, Pablo Borges, Boettcher, Michael E., Boulet, Gilles, Breinl, Korbinian, Brilly, Mitja, Brocca, Luca, Buytaert, Wouter, Castellarin, Attilio, Castelletti, Andrea, Chen, Xiaohong, Chen, Yangbo, Chen, Yuanfang, Chifflard, Peter, Claps, Pierluigi, Clark, Martyn P., Collins, Adrian L., Croke, Barry, Dathe, Annette, David, Paula C., de Barros, Felipe P. J., de Rooij, Gerrit, Di Baldassarre, Giuliano, Driscoll, Jessica M., Duethmann, Doris, Dwivedi, Ravindra, Eris, Ebru, Farmer, William H., Feiccabrino, James, Ferguson, Grant, Ferrari, Ennio, Ferraris, Stefano, Fersch, Benjamin, Finger, David, Foglia, Laura, Fowler, Keirnan, Gartsman, Boris, Gascoin, Simon, Gaume, Eric, Gelfan, Alexander, Geris, Josie, Gharari, Shervan, Gleeson, Tom, Glendell, Miriam, Bevacqua, Alena Gonzalez, Gonzalez-Dugo, Maria P., Grimaldi, Salvatore, Gupta, A. B., Guse, Bjoern, Han, Dawei, Hannah, David, Harpold, Adrian, Haun, Stefan, Heal, Kate, Helfricht, Kay, Herrnegger, Mathew, Hipsey, Matthew, Hlavacikova, Hana, Hohmann, Clara, Holko, Ladislav, Hopkinson, Christopher, Hrachowitz, Markus, Illangasekare, Tissa H., Inam, Azhar, Innocente, Camyla, Istanbulluoglu, Erkan, Jarihani, Ben, Kalantari, Zahra, Kalvans, Andis, Khanal, Sonu, Khatami, Sina, Kiesel, Jens, Kirkby, Mike, Knoben, Wouter, Kochanek, Krzysztof, Kohnova, Silvia, Kolechkina, Alla, Krause, Stefan, Kreamer, David, Kreibich, Heidi, Kunstmann, Harald, Lange, Holger, Liberato, Margarida L. R., Lindquist, Eric, Link, Timothy, Liu, Junguo, Loucks, Daniel Peter, Luce, Charles, Mahe, Gil, Makarieva, Olga, Malard, Julien, Mashtayeva, Shamshagul, Maskey, Shreedhar, Mas-Pla, Josep, Mavrova-Guirguinova, Maria, Mazzoleni, Maurizio, Mernild, Sebastian, Misstear, Bruce Dudley, Montanari, Alberto, Mueller-Thomy, Hannes, Nabizadeh, Alireza, Nardi, Fernando, Neale, Christopher, Nesterova, Nataliia, Nurtaev, Bakhram, Odongo, Vincent, Panda, Subhabrata, Pande, Saket, Pang, Zhonghe, Papacharalampous, Georgia, Perrin, Charles, Pfister, Laurent, Pimentel, Rafael, Polo, Maria J., Post, David, Sierra, Cristina Prieto, Ramos, Maria-Helena, Renner, Maik, Reynolds, Eduardo, Ridolfi, Elena, Rigon, Riccardo, Riva, Monica, Robertson, David E., Rosso, Renzo, Roy, Tirthankar, Sa, Joao H. M., Salvadori, Gianfausto, Sandells, Mel, Schaefli, Bettina, Schumann, Andreas, Scolobig, Anna, Seibert, Jan, Servat, Eric, Shafiei, Mojtaba, Sharma, Ashish, Sidibe, Moussa, Sidle, Roy C., Skaugen, Thomas, Smith, Hugh, Spiessl, Sabine M., Stein, Lina, Steinsland, Ingelin, Strasser, Ulrich, Su, Bob, Szolgay, Jan, Tarboton, David, Tauro, Flavia, Thirel, Guillaume, Tian, Fuqiang, Tong, Rui, Tussupova, Kamshat, Tyralis, Hristos, Uijlenhoet, Remko, van Beek, Rens, van der Ent, Ruud J., van der Ploeg, Martine, Van Loon, Anne F., van Meerveld, Ilja, van Nooijen, Ronald, van Oel, Pieter R., Vidal, Jean-Philippe, von Freyberg, Jana, Vorogushyn, Sergiy, Wachniew, Przemyslaw, Wade, Andrew J., Ward, Philip, Westerberg, Ida K., White, Christopher, Wood, Eric F., Woods, Ross, Xu, Zongxue, Yilmaz, Koray K., Zhang, Yongqiang, Bloeschl, Gunter, Bierkens, Marc F. P., Chambel, Antonio, Cudennec, Christophe, Destouni, Georgia, Fiori, Aldo, Kirchner, James W., McDonnell, Jeffrey J., Savenije, Hubert H. G., Sivapalan, Murugesu, Stumpp, Christine, Toth, Elena, Volpi, Elena, Carr, Gemma, Lupton, Claire, Salinas, Jose, Szeles, Borbala, Viglione, Alberto, Aksoy, Hafzullah, Allen, Scott T., Amin, Anam, Andreassian, Vazken, Arheimer, Berit, Aryal, Santosh K., Baker, Victor, Bardsley, Earl, Barendrecht, Marlies H., Bartosova, Alena, Batelaan, Okke, Berghuijs, Wouter R., Beven, Keith, Blume, Theresa, Bogaard, Thom, de Amorim, Pablo Borges, Boettcher, Michael E., Boulet, Gilles, Breinl, Korbinian, Brilly, Mitja, Brocca, Luca, Buytaert, Wouter, Castellarin, Attilio, Castelletti, Andrea, Chen, Xiaohong, Chen, Yangbo, Chen, Yuanfang, Chifflard, Peter, Claps, Pierluigi, Clark, Martyn P., Collins, Adrian L., Croke, Barry, Dathe, Annette, David, Paula C., de Barros, Felipe P. J., de Rooij, Gerrit, Di Baldassarre, Giuliano, Driscoll, Jessica M., Duethmann, Doris, Dwivedi, Ravindra, Eris, Ebru, Farmer, William H., Feiccabrino, James, Ferguson, Grant, Ferrari, Ennio, Ferraris, Stefano, Fersch, Benjamin, Finger, David, Foglia, Laura, Fowler, Keirnan, Gartsman, Boris, Gascoin, Simon, Gaume, Eric, Gelfan, Alexander, Geris, Josie, Gharari, Shervan, Gleeson, Tom, Glendell, Miriam, Bevacqua, Alena Gonzalez, Gonzalez-Dugo, Maria P., Grimaldi, Salvatore, Gupta, A. B., Guse, Bjoern, Han, Dawei, Hannah, David, Harpold, Adrian, Haun, Stefan, Heal, Kate, Helfricht, Kay, Herrnegger, Mathew, Hipsey, Matthew, Hlavacikova, Hana, Hohmann, Clara, Holko, Ladislav, Hopkinson, Christopher, Hrachowitz, Markus, Illangasekare, Tissa H., Inam, Azhar, Innocente, Camyla, Istanbulluoglu, Erkan, Jarihani, Ben, Kalantari, Zahra, Kalvans, Andis, Khanal, Sonu, Khatami, Sina, Kiesel, Jens, Kirkby, Mike, Knoben, Wouter, Kochanek, Krzysztof, Kohnova, Silvia, Kolechkina, Alla, Krause, Stefan, Kreamer, David, Kreibich, Heidi, Kunstmann, Harald, Lange, Holger, Liberato, Margarida L. R., Lindquist, Eric, Link, Timothy, Liu, Junguo, Loucks, Daniel Peter, Luce, Charles, Mahe, Gil, Makarieva, Olga, Malard, Julien, Mashtayeva, Shamshagul, Maskey, Shreedhar, Mas-Pla, Josep, Mavrova-Guirguinova, Maria, Mazzoleni, Maurizio, Mernild, Sebastian, Misstear, Bruce Dudley, Montanari, Alberto, Mueller-Thomy, Hannes, Nabizadeh, Alireza, Nardi, Fernando, Neale, Christopher, Nesterova, Nataliia, Nurtaev, Bakhram, Odongo, Vincent, Panda, Subhabrata, Pande, Saket, Pang, Zhonghe, Papacharalampous, Georgia, Perrin, Charles, Pfister, Laurent, Pimentel, Rafael, Polo, Maria J., Post, David, Sierra, Cristina Prieto, Ramos, Maria-Helena, Renner, Maik, Reynolds, Eduardo, Ridolfi, Elena, Rigon, Riccardo, Riva, Monica, Robertson, David E., Rosso, Renzo, Roy, Tirthankar, Sa, Joao H. M., Salvadori, Gianfausto, Sandells, Mel, Schaefli, Bettina, Schumann, Andreas, Scolobig, Anna, Seibert, Jan, Servat, Eric, Shafiei, Mojtaba, Sharma, Ashish, Sidibe, Moussa, Sidle, Roy C., Skaugen, Thomas, Smith, Hugh, Spiessl, Sabine M., Stein, Lina, Steinsland, Ingelin, Strasser, Ulrich, Su, Bob, Szolgay, Jan, Tarboton, David, Tauro, Flavia, Thirel, Guillaume, Tian, Fuqiang, Tong, Rui, Tussupova, Kamshat, Tyralis, Hristos, Uijlenhoet, Remko, van Beek, Rens, van der Ent, Ruud J., van der Ploeg, Martine, Van Loon, Anne F., van Meerveld, Ilja, van Nooijen, Ronald, van Oel, Pieter R., Vidal, Jean-Philippe, von Freyberg, Jana, Vorogushyn, Sergiy, Wachniew, Przemyslaw, Wade, Andrew J., Ward, Philip, Westerberg, Ida K., White, Christopher, Wood, Eric F., Woods, Ross, Xu, Zongxue, Yilmaz, Koray K., and Zhang, Yongqiang

Abstract

This paper is the outcome of a community initiative to identify major unsolved scientific problems in hydrology motivated by a need for stronger harmonisation of research efforts. The procedure involved a public consultation through online media, followed by two workshops through which a large number of potential science questions were collated, prioritised, and synthesised. In spite of the diversity of the participants (230 scientists in total), the process revealed much about community priorities and the state of our science: a preference for continuity in research questions rather than radical departures or redirections from past and current work. Questions remain focused on the process-based understanding of hydrological variability and causality at all space and time scales. Increased attention to environmental change drives a new emphasis on understanding how change propagates across interfaces within the hydrological system and across disciplinary boundaries. In particular, the expansion of the human footprint raises a new set of questions related to human interactions with nature and water cycle feedbacks in the context of complex water management problems. We hope that this reflection and synthesis of the 23 unsolved problems in hydrology will help guide research efforts for some years to come.

Published
2019
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25. Effects of the hydraulic conductivity microstructure on macrodispersivity

Author

Di Dato, Mariaines, de Barros, Felipe P. J., Fiori, Aldo, BELLIN, Alberto, Di Dato, Mariaine, de Barros, Felipe P. J., Fiori, Aldo, and Bellin, Alberto

Subjects
first-order, groundwater flow, heterogeneous aquifer, macrodispersion, microstructure, transport, Water Science and Technology
Abstract

Heterogeneity of the hydraulic properties is one of the main causes of the seemingly random distribution of solute concentration observed in contaminated aquifers, with macrodispersivity providing a global measure of spreading. Earlier studies on transport of solutes in heterogeneous formations, either theoretical or numerical, expressed dispersivity as a function of the geostatistical properties of the hydraulic conductivity K. In most cases, K follows a second-order statistical characterization, which may not be adequate when heterogeneity is high. In this work, we adopt the Multi-Indicator Model–Self Consistent Approach (MIMSCA) to compute the longitudinal and transverse macrodispersivity. This methodology enables to model the K field by using geological inclusions of different shapes and orientation (defined here as the microstructure), while replicating the heterogeneous macrostructure obtained by the second-order statistics. The above scheme attempts to reproduce the effect on macrodispersion of different distribution and orientation of local facies, and for instance it may represent the orientation and spatial features of the layers that are often observed in aquifers. The relevant impact of the microstructure on effective conductivity, longitudinal and transverse macrodispersivities is analyzed and discussed, for both binary and lognormally distributed K fields.

Published
2016

26. Transport analysis in deformable porous media through integral transforms.

Author

Bonazzi, Alessandra, Jha, Birendra, and de Barros, Felipe P. J.

Subjects
POROUS materials, GENERALIZED integrals, INTEGRAL transforms, COMPRESSIBILITY, POROELASTICITY
Abstract

Geomechanical deformation can alter the flow field that impacts solute mass fluxes. Despite its importance, the effects of the coupling between geomechanical deformation and the flow field on solute transport behavior are not fully known. In this paper, we study the impact of this coupling on the solute concentration distribution. The concentration field is semianalytically derived by making use of the generalized integral transform technique. We apply the semianalytical solution to two uniaxial consolidation problems, the classical Terzaghi's problem with a constant load and the case of periodic loading of a porous deformable layer. Our results indicate that geomechanical parameters, such as the Skempton's coefficient and the soil compressibility, can affect the peak concentration as well as the spatial moments of solute plume. In case of periodic loading, we show that the frequency of loading also plays a key role in regulating the temporal dynamics of the concentration field. [ABSTRACT FROM AUTHOR]

Published
2021
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32. Coupled continuous-time random walks for fluid stretching in two-dimensional heterogeneous media

Author

European Research Council, Dentz, Marco, Lester, Daniel R., Le Borgne, Tanguy, De Barros, Felipe P J, European Research Council, Dentz, Marco, Lester, Daniel R., Le Borgne, Tanguy, and De Barros, Felipe P J

Abstract

We study the relation between flow structure and fluid deformation in steady flows through two-dimensional heterogeneous media, which are characterized by a broad spectrum of stretching behaviors, ranging from sub- to superlinear. We analyze these behaviors from first principles, which uncovers intermittent shear events to be at the origin of subexponential stretching. We derive explicit expressions for Lagrangian deformation and demonstrate that stretching obeys a coupled continuous-time random walk, which for broad distributions of flow velocities becomes a Lévy walk. The derived model provides a direct link between the flow and deformation statistics, and a natural way to quantify the impact of intermittent shear events on the stretching behavior. © 2016 American Physical Society.

Published
2016

41. An indirect assessment on the impact of connectivity of conductivity classes upon longitudinal asymptotic macrodispersivity

Author

Fiori, Aldo, Boso, Francesca, de Barros, Felipe P. J., De Bartolo, Samuele, Frampton, Andrew, Severino, Gerardo, Suweis, Samir, Dagan, Gedeon, Fiori, Aldo, Boso, Francesca, de Barros, Felipe P. J., De Bartolo, Samuele, Frampton, Andrew, Severino, Gerardo, Suweis, Samir, and Dagan, Gedeon

Abstract

Solute transport takes place in heterogeneous porous formations, with the log conductivity, Y = ln K, modeled as a stationary random space function of given univariate normal probability density function (pdf) with mean < Y >, variance sigma(2)(Y), and integral scale I-Y. For weak heterogeneity, the above mentioned quantities completely define the first-order approximation of the longitudinal macrodispersivity sigma(L) = sigma I-2(Y)Y. However, in highly heterogeneous formations, nonlinear effects which depend on the multipoint joint pdf of Y, impact alpha(L). Most of the past numerical simulations assumed a multivariate normal distribution (MVN) of Y values. The main aim of this study is to investigate the impact of deviations from the MVN structure upon alpha(L). This is achieved by using the concept of spatial correlations of different Y classes, the latter being defined as the space domain where Y falls in the generic interval [Y,Y + Delta Y]. The latter is characterized by a length scale lambda(Y), reflecting the degree of connectivity of the domain (the concept is similar to the indicator variograms). We consider both "symmetrical" and "non-symmetrical" structures, for which lambda(Y') = lambda(-Y') (similar to the MVN), and lambda(Y') not equal lambda(-Y'), respectively, where Y' = Y - < Y >. For example, large Y zones may have high spatial correlation, while low Y zones are poorly correlated, or vice versa. The impact of lambda(Y) on alpha(L) is investigated by adopting a structure model which has been used in the past in order to investigate flow and transport in highly heterogeneous media. It is found that the increased correlation in the low conductive zones with respect to the high ones generally leads to a significant increase in alpha(L), for the same global I-Y. The finding is explained by the solute retention occurring in low Y zones, which has a larger effect on solute spreading than high Y zones. Conversely, alpha(L) decreases when the, QC 20101206

Published
2010
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