Boris Faybishenko | Lawrence Berkeley National Laboratory (original) (raw)

Papers by Boris Faybishenko

Dynamics of Fluids and Transport in Complex Fractured-Porous Systems, 2015

Transport in Porous Media, 2022

Understanding gas migration in compacted clay materials, e.g., bentonite and claystone, is import... more Understanding gas migration in compacted clay materials, e.g., bentonite and claystone, is important for the design and performance assessment of an engineered barrier system of a radioactive waste repository system, as well as many practical applications. Existing field and laboratory data on gas migration processes in low-permeability clay materials demonstrate the complexity of flow and transport processes, including various types of instabilities, caused by nonlinear dynamics of coupled processes of liquid-gas exchange, dilation, fracturing, fracture healing, etc., which cannot be described by classical models of fluid dynamics in porous media. We here show that the complexity of gas migration processes can be explained using a phenomenological concept of nonlinear dynamics and deterministic chaos theory. To do so, we analyzed gas pressure and gas influx (i.e., input) and outflux (i.e., output), recorded during the gas injection experiment in the compact Mx80-D bentonite sample, and calculated a set of the diagnostic parameters of nonlinear dynamics and chaos, such a global embedding dimension, a correlation dimension, an information dimension, and a spectrum of Lyapunov exponents, as well as plotted 2D and 3D pseudophase-space strange attractors, based on the univariate influx and outflux time series data. These results indicate the presence of phenomena of low-dimensional deterministic chaotic behavior of gas migration in bentonite. In particular, during the onset of gas influx in the bentonite core, before the breakthrough, the development of gas flow pathways is characterized by the process of chaotic gas diffusion. After the breakthrough, with inlet-to-outlet movement of gas, the prevailing process is chaotic advection. During the final phase of the experiment, with no influx to the sample, the relaxation pattern of gas outflux is resumed back to a process of chaotic diffusion. The types of data analysis and a proposed phenomenological model can be used to establish the basic principles of experimental data-gathering, modeling predictions, and a research design.

Vadose Zone Journal, Feb 1, 2004

The results of a series of ponded infiltration tests in variably saturated fractured basalt at Bo... more The results of a series of ponded infiltration tests in variably saturated fractured basalt at Box Canyon, Idaho, were used to build confidence in conceptual and numerical modeling approaches used to simulate infiltration in fractured rock. Specifically, we constructed a dual-permeability model using TOUGH2 to represent both the matrix and fracture continua of the upper basalt flow at the Box Canyon site. A consistent set of hydrogeological parameters was obtained by calibrating the model to infiltration front arrival times in the fracture continuum as inferred from bromide samples collected from fracture/borehole intersections observed during the infiltrating tests. These parameters included the permeability of the fracture and matrix continua, the interfacial area between the fracture and matrix continua, and the porosity of the fracture continuum. To calibrate the model, we multiplied the fracture-matrix interfacial area by a factor between 0.1 and 0.01 to reduce imbibition of water from the fracture continuum into the matrix continuum during the infiltration tests. Furthermore, the porosity of the fracture continuum, as calculated using the fracture aperture inferred from pneumatic-test permeabilities, was increased by a factor of 50 yielding porosity values for the upper basalt flow in the range of 0.01 to 0.02. The fracture-continuum porosity was a highly sensitive parameter controlling the arrival times of the simulated infiltration fronts. Porosity values are consistent with those determined during the Large-Scale Aquifer Pumping and Infiltration Test at the Idaho National Engineering and Environmental Laboratory.

Goldschmidt2021 abstracts, 2021

$Research paper thumbnail of Detecting dynamic causal inference in nonlinear two-phase fracture flow$

Advances in Water Resources, 2017

The Granger causality test is used to identify the dynamic causality of nonlinear chaotic gas-liq... more The Granger causality test is used to identify the dynamic causality of nonlinear chaotic gas-liquid interactions for flow through fractured media. • A hypothesis concerning the mutual forward and backward gas-liquid interactions for two-phase flow through the fracture is confirmed. • The causality loop diagram describes a forward (positive) and backward (negative) links of the inlet and outlet gas and liquid pressures.

Goldschmidt Abstracts, 2020

HAL (Le Centre pour la Communication Scientifique Directe), Aug 5, 2018

International audienceBackground/Question/Methods Tropical forest responses to moisture remain po... more International audienceBackground/Question/Methods Tropical forest responses to moisture remain poorly understood, in part because of the large diversity of plant hydraulic traits found therein. Changing moisture regimes, such as more frequent drought events, are expected to interact with these diverse hydraulic traits and other requirements of tropical trees in complex ways, making prediction of ecosystem-scale responses and community compositional trajectories difficult. A first step towards discerning such responses is in the analysis of how plant hydraulic and edaphic conditions control trajectories of individual trees’ water use over pre-drought, drought, and recovery periods. We took advantage of the 2015-2016 ENSO event, which induced drought over much of the tropics, to collect sap flow data on 47 canopy and numerous sub-canopy trees across nine sites in Latin America varying in annual precipitation from 1700 mm to > 3000 mm. This enabled us to determine a range of responses to changes in moisture, both atmospheric (VPD) and in soil. Where available, via measurements on conspecific individuals or species-mean values in trait databases, plant hydraulic traits were associated with individual sap flux trajectories, in addition to site-specific soil properties and climate. Results/Conclusions We found a large heterogeneity of sap flow responses during the ENSO within and among study regions. The diversity of strategies to deal with drought stress was partially explained by species functional traits, background climate and intensity of soil water depletion during the ENSO. Preliminary simulations of drought responses using the Community Land Model coupled to the hydraulically-enabled Functionally Assembled Terrestrial Ecosystem Simulator (CLM-FATES-Hydro) were used to demonstrate multiple mechanisms, both edaphic- and plant trait-related, responsible for the divergence in observed sap flow responses, as well as highlight critical field measurements needed to discern among these mechanisms

$Research paper thumbnail of Nonlinear dynamics in flow through unsaturated fractured-porous media: Status and perspectives$

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Nov 27, 2002

The need has long been recognized to improve predictions of flow and transport in partially satur... more The need has long been recognized to improve predictions of flow and transport in partially saturated heterogeneous soils and fractured rock of the vadose zone for many practical applications, such as remediation of contaminated sites, nuclear waste disposal in geological formations, and climate predictions. Until recently, flow and transport processes in heterogeneous subsurface media with oscillating irregularities were assumed to be random and were not analyzed using methods of nonlinear dynamics. The goals of this paper are to review the theoretical concepts, present the results, and provide perspectives on investigations of flow and transport in unsaturated heterogeneous soils and fractured rock, using the methods of nonlinear dynamics and deterministic chaos. The results of laboratory and field investigations indicate that the nonlinear dynamics of flow and transport processes in unsaturated soils and fractured rocks arise from the dynamic feedback and competition between various nonlinear physical 29 processes along with complex geometry of flow paths. 30 Although direct measurements of variables characterizing 31 the individual flow processes are not technically feasible, 32 their cumulative effect can be characterized by analyzing 33 time series data using the models and methods of nonlinear 34 dynamics and chaos. Identifying flow through soil or 35 rock as a nonlinear dynamical system is important for 36 developing appropriate short-and long-time predictive 37 models, evaluating prediction uncertainty, assessing the 38 spatial distribution of flow characteristics from time series 39 data, and improving chemical transport simulations. 40 Inferring the nature of flow processes through the methods 41 of nonlinear dynamics could become widely used in 42 different areas of the earth sciences.