Kordilla, Jannes

[["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Vadose Zone Journal"],["dc.bibliographiccitation.volume","18"],["dc.contributor.author","Shigorina, Elena"],["dc.contributor.author","Tartakovsky, Alexandre M."],["dc.contributor.author","Kordilla, Jannes"],["dc.date.accessioned","2019-07-04T08:33:12Z"],["dc.date.available","2019-07-04T08:33:12Z"],["dc.date.issued","2019"],["dc.description.abstract","This work investigates small-scale infiltration dynamics in smooth and rough single fractures using a three-dimensional multiphase pairwise-force smoothed particle hydrodynamics (PF-SPH) model. Gravity-driven infiltration instabilities in fractures under unsaturated conditions can significantly influence the arrival time of tracers or contaminants, and the rapid and localized recharge dynamics in fractured–porous aquifer systems. Here, we study the influence of roughness and injection rate on fluid flow modes and flow velocity. Three types of fractures are considered with different degrees of roughness, including a smooth fracture. Both the rough and smooth fractures exhibit flow instabilities, fingering, and intermittent flow regimes for low infiltration rates. In agreement with theoretical predictions, a flat fluid front is achieved when the flux q supplied to a fracture is larger than the gravitationally driven saturated flux [q > kρg/μcos(φ), where k is the intrinsic permeability of the fracture, ρ is a density, μ is the viscosity, and φ is the fracture inclination angle measured from the vertical direction]. To characterize the flow instability, we calculate standard deviations of velocity along the fracture width. For the considered infiltration rates, we find that an increase in roughness decreases the flow velocity and increases the standard deviation of velocity. This is caused by a higher likelihood of flow discontinuities in the form of fingering and/or snapping rivulets. To validate our unsaturated flow simulations in fractures, we estimate the scaling of specific discharge with normalized finger velocity, compute the relationship between fingertip length and scaled finger velocity, and find good agreement with experimental results."],["dc.identifier.doi","10.2136/vzj2018.08.0159"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/16238"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/58007"],["dc.language.iso","en"],["dc.notes.intern","Open Access"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","final"],["dc.relation.issn","1539-1663"],["dc.rights","CC BY-NC-ND 4.0"],["dc.rights.uri","https://creativecommons.org/licenses/by-nc-nd/4.0"],["dc.title","Investigation of Gravity-Driven Infiltration Instabilities in Smooth and Rough Fractures Using a Pairwise-Force Smoothed Particle Hydrodynamics Model"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Vadose Zone Journal"],["dc.bibliographiccitation.volume","18"],["dc.contributor.author","Noffz, Torsten"],["dc.contributor.author","Dentz, Marco"],["dc.contributor.author","Kordilla, Jannes"],["dc.date.accessioned","2019-07-09T11:50:27Z"],["dc.date.available","2019-07-09T11:50:27Z"],["dc.date.issued","2019"],["dc.description.abstract","Infiltration and recharge dynamics in fractured aquifer systems often strongly deviate from diffuse Darcy–Buckingham type flows due to the existence of a complex gravity-driven flow component along fractures, fracture networks, and fault zones. The formation of preferential flow paths in the unsaturated or vadose zone can trigger rapid mass fluxes, which are difficult to recover by volume-effective modeling approaches (e.g., the Richards equation) due to the nonlinear nature of free-surface flows and mass partitioning processes at unsaturated fracture intersections. In this study, well-controlled laboratory experiments enabled the isolation of single aspects of the mass redistribution process that ultimately affect travel time distributions across scales. We used custom-made acrylic cubes (20 by 20 by 20 cm) in analog percolation experiments to create simple wide-aperture fracture networks intersected by one or multiple horizontal fractures. A high-precision multichannel dispenser produced gravity-driven free-surface flow (droplets or rivulets) at flow rates ranging from 1 to 5 mL min−1. Total inflow rates were kept constant while the fluid was injected via 15 (droplet flow) or three inlets (rivulet flow) to reduce the impact of erratic flow dynamics. Normalized fracture inflow rates were calculated and compared for aperture widths of 1 and 2.5 mm. A higher efficiency in filling an unsaturated fracture by rivulet flow observed in former studies was confirmed. The onset of a capillary-driven Washburn-type flow was determined and recovered by an analytical solution. To upscale the dynamics and enable the prediction of mass partitioning for arbitrary-sized fracture cascades, a Gaussian transfer function was derived that reproduces the repetitive filling of fractures, where rivulet flow is the prevailing regime. Results show good agreement with experimental data for all tested aperture widths."],["dc.description.sponsorship","Open-Access-Publikationsfonds 2019"],["dc.identifier.doi","10.2136/vzj2018.08.0155"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/15945"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/59778"],["dc.language.iso","en"],["dc.notes.intern","Merged from goescholar"],["dc.notes.intern","In goescholar not merged with http://resolver.sub.uni-goettingen.de/purl?gs-1/16068 but duplicate"],["dc.relation","info:eu-repo/grantAgreement/EC/FP7/617511/EU//MHETSCALE"],["dc.rights","CC BY-NC-ND 4.0"],["dc.rights.uri","https://creativecommons.org/licenses/by-nc-nd/4.0"],["dc.subject.ddc","550"],["dc.title","Analogue Fracture Experiments and Analytical Modeling of Unsaturated Percolation Dynamics in Fracture Cascades"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","Vadose Zone Journal"],["dc.bibliographiccitation.volume","21"],["dc.contributor.author","Rüdiger, Florian"],["dc.contributor.author","Dentz, Marco"],["dc.contributor.author","Nimmo, John"],["dc.contributor.author","Kordilla, Jannes"],["dc.date.accessioned","2022-04-01T10:02:14Z"],["dc.date.available","2022-04-01T10:02:14Z"],["dc.date.issued","2022"],["dc.description.sponsorship","Open-Access-Publikationsfonds 2022"],["dc.description.sponsorship","Open-Access-Publikationsfonds 2022"],["dc.identifier.doi","10.1002/vzj2.20177"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/105858"],["dc.language.iso","en"],["dc.notes.intern","DOI-Import GROB-530"],["dc.relation.eissn","1539-1663"],["dc.relation.issn","1539-1663"],["dc.rights","CC BY 4.0"],["dc.title","Laboratory experiments and dual‐domain modeling of infiltration dynamics in partially saturated fractured porous media"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","3909"],["dc.bibliographiccitation.issue","10"],["dc.bibliographiccitation.journal","HYDROLOGY AND EARTH SYSTEM SCIENCES"],["dc.bibliographiccitation.lastpage","3923"],["dc.bibliographiccitation.volume","16"],["dc.contributor.author","Kordilla, Jannes"],["dc.contributor.author","Sauter, M."],["dc.contributor.author","Reimann, Thomas"],["dc.contributor.author","Geyer, Tobias"],["dc.date.accessioned","2018-11-07T09:14:50Z"],["dc.date.available","2018-11-07T09:14:50Z"],["dc.date.issued","2012"],["dc.description.abstract","The objective of this work is the simulation of saturated and unsaturated flow in a karstified aquifer using a double continuum approach. The HydroGeoSphere code (Therrien et al., 2006) is employed to simulate spring discharge with the Richards equations and van Genuchten parameters to represent flow in the (1) fractured matrix and (2) conduit continuum coupled by a linear exchange term. Rapid vertical small-scale flow processes in the unsaturated conduit continuum are accounted for by applying recharge boundary conditions at the bottom of the saturated model domain. An extensive sensitivity analysis is performed on single parameters as well as parameter combinations. The transient hydraulic response of the karst spring is strongly controlled by the matrix porosity as well as the van Genuchten parameters of the unsaturated matrix, which determine the head dependent inter-continuum water transfer when the conduits are draining the matrix. Sensitivities of parameter combinations partially reveal a non-linear dependence over the parameter space. This can be observed for parameters not belonging to the same continuum as well as combinations, which involve the exchange parameter, showing that results of the double continuum model may depict a certain degree of ambiguity. The application of van Genuchten parameters for simulation of unsaturated flow in karst systems is critically discussed."],["dc.identifier.doi","10.5194/hess-16-3909-2012"],["dc.identifier.isi","000310474300028"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/9516"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/27516"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Copernicus Gesellschaft Mbh"],["dc.relation.issn","1607-7938"],["dc.relation.issn","1027-5606"],["dc.rights","CC BY-NC 3.0"],["dc.rights.uri","https://creativecommons.org/licenses/by-nc/3.0"],["dc.title","Simulation of saturated and unsaturated flow in karst systems at catchment scale using a double continuum approach"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]