•A new generalized Grass-type formulation for non-equilibrium bedload transport is proposed.•The 1D SW and non-equilibrium bedload equations are solved using a ARoe’s scheme.•Effects of finite-depth ...erodible layers are accounted by means of a corrector solid flux term.•A new reconstruction strategy for the approximate solution is proposed to avoid unphysical over-erosion problems.•The proposed scheme offers good predictions ensuring mass conservation and efficient time steps.
Finite-depth sediment layers are common in natural water bodies. The presence of underlying bedrock strata covered by erodible bed layers is ubiquitous in rivers and estuaries. In the last years, the development of models based on the non-capacity sediment transport assumption, also called non-equilibrium assumption, has offered a new theoretical background to deal with complex non-erodible bed configurations and the associated numerical problems. Bedload non-capacity sediment transport models consider that the actual solid transport state can be different from the equilibrium state and depending on the temporal evolution of the flow. The treatment of finite-depth erodible bed layers, i.e. partially erodible beds, in bedload models based on the equilibrium approach has usually been made using numerical fixes, which correct the unphysical results obtained in some cases. Generally, the presence of a finite-depth erodible layer implies the introduction of a kind of non-equilibrium condition in the bedload transport state. Nevertheless, this common natural bed configuration has not been previously considered in the development of numerical models. In this work, a finite volume model (FVM) for bedload transport based on non-capacity approach and dealing with finite-depth erodible layers is proposed. New expressions for the actual bedload transport rate and the net exchange flux through the static-moving bed layers interface are used to develop a numerical scheme which solves the coupled shallow water and non-capacity bedload transport system of equations. The reconstruction of the intermediate states for the local Riemann problem at each intercell edge is designed to correctly model the presence of non-erodible strata, avoiding the appearance of unphysical results in the approximate solution without reducing the time step. The new coupled scheme is tested against laboratory benchmarking experiments in order to demonstrate its stability and accuracy, pointing out the properties of both equilibrium and non-equilibrium formulations.
STUDY QUESTION
What is the potential impact of follicular fluid (FF) from infertile women with mild endometriosis (ME) on oocyte quality, especially on nuclear maturation and the meiotic spindle?
...SUMMARY ANSWER
FF from infertile women with ME may compromise nuclear maturation and the meiotic spindles of in vitro matured bovine oocytes.
WHAT IS KNOWN ALREADY
Controversial studies have suggested that impaired oocyte quality may be involved in the pathogenesis of endometriosis-related infertility. Moreover, some studies have demonstrated alterations in the composition of FF from infertile women with endometriosis. However, to date no study has evaluated the effect of FF from infertile women with ME on the genesis of meiotic oocyte anomalies.
STUDY DESIGN, SIZE, DURATION
We performed an experimental study. Samples of FF were obtained from February 2009 to February 2011 from 22 infertile women, 11 with ME and 11 with tubal or male factors of infertility (control group), who underwent ovarian stimulation for ICSI at our university IVF Unit. From March 2011 to February 2012 we performed in vitro maturation (IVM) experiments using immature bovine oocytes as described below.
PARTICIPANTS/MATERIALS, SETTING, METHODS
FF free of blood and containing a mature oocyte was obtained from 22 infertile women during oocyte retrieval for ICSI. Immature bovine oocytes underwent IVM in the absence of FF (No-FF) and in the presence of four concentrations (1, 5, 10 and 15%) of FF from infertile women without endometriosis (C-FF) and with ME (ME-FF). Eleven replicates were performed, each one using FF from a control patient and a patient with ME. Each FF sample was used in only one experiment. After 22–24 h of IVM, oocytes were denuded, fixed and immunostained for morphological visualization of microtubules and chromatin by confocal microscopy.
MAIN RESULTS AND THE ROLE OF CHANCE
A total of 1324 cumulus–oocyte complexes were matured in vitro. Of these, 1128 were fixed and 1048 were analyzed by confocal microscopy. The percentage of meiotically normal oocytes was significantly higher for oocytes that underwent IVM in the absence of FF (No-FF; 76.5%) and in the presence of 1% (80.9%), 5% (76.6%), 10% (75%) and 15% (76.2%) C-FF than in oocytes that underwent IVM in the presence of 1% (44.4%), 5% (36.7%), 10% (45.5%) and 15% (51.2%) ME-FF (P < 0.01). No differences were observed among FF concentrations within each group. When the four concentrations from each group were pooled, the number of oocytes in metaphase I stage was significantly higher in the ME-FF (50 oocytes) than in the C-FF (29 oocytes) group and the percentage of meiotic abnormalities was significantly higher when oocytes were matured with ME-FF (55.8%) than with C-FF (23.1%), P < 0.01.
LIMITATIONS, REASONS FOR CAUTION
Owing to the strict selection criteria for FF donors, this study had a small sample size (11 cases and 11 controls), and thus further investigations using a large cohort of patients are needed to confirm these results. In addition, data obtained from studies using animal models may not necessarily be extrapolated to humans and studies evaluating in vivo matured oocytes from infertile women with ME are important to confirm our results.
WIDER IMPLICATIONS OF THE FINDINGS
Our results open new insights into the pathogenic mechanisms of infertility related to mild endometriosis, suggesting that FF from infertile women with mild endometriosis may be involved in the worsening of oocyte quality of these women.
STUDY FUNDING/COMPETING INTEREST(S)
This study was supported by the National Council for Scientific and Technological Development (CNPq), Brazil. The authors declare no conflicts of interest.
In three experiments, we conceptually replicated and extended the spillover bias in judgments of diversity that was first reported by Daniels et al. (
2017
,
Organizational Behavior and Human ...Decision Processes, 139
, 92–105). In the first experiment, we showed that judgments of the ethnoracial diversity of groups of people were affected by the gender diversity of those people. In the second experiment, we extended this result to nonsocial stimuli by showing that judgments of the size diversity and size variability of groups of circles were affected by the color diversity of those circles. In the third experiment, we showed that judgments of the ethnoracial diversity of groups of people were affected by the color diversity of a group of circles in the background. These results suggest that diversity spillover bias is an extremely general phenomenon that occurs for both social and nonsocial judgments of diversity and variability. We propose that it occurs because people use the overall perceived diversity in a set of stimuli as a cue to judge diversity on any specific dimension.
The well-balanced property that ensures quiescent equilibrium when solving the shallow-water equations with varying topography is extended in this work to ensure numerically a constant level of ...energy in steady cases with velocity when necessary. This is done in the context of augmented solvers that consider in their definition the presence of a discontinuous bed. In order to guarantee a constant energy state a proper integral approach of the bed source term is presented. This approach is systematically assessed via a series of steady test cases and Riemann problems including the resonance regime.
•A GPU implementation of a FV method for the 2D Shallow Water Equations is presented.•Structured and unstructured meshes allow different implementations.•NVIDIA C2070 GPU is compared against Intel ...Core 2 Quad Processor.•The basic GPU implementation obtains between 20× and 30× of speed-up.•Some strategies on the mesh order allow to double the performance, reaching 50×.
This work is related with the implementation of a finite volume method to solve the 2D Shallow Water Equations on Graphic Processing Units (GPU). The strategy is fully oriented to work efficiently with unstructured meshes which are widely used in many fields of Engineering. Due to the design of the GPU cards, structured meshes are better suited to work with than unstructured meshes. In order to overcome this situation, some strategies are proposed and analyzed in terms of computational gain, by means of introducing certain ordering on the unstructured meshes. The necessity of performing the simulations using unstructured instead of structured meshes is also justified by means of some test cases with analytical solution.
The movement of poorly sorted material over steep areas constitutes a hazardous environmental problem. Computational tools help in the understanding and predictions of such landslides. The main ...drawback is the high computational effort required for obtaining accurate numerical solutions due to the high number of cells involved in the calculus. In order to overcome this problem, this work proposes the use of GPUs for decreasing significantly the CPU simulation time. The numerical scheme implemented in GPU is based on a finite volume scheme and it was validated in previous work with exact solutions and experimental data. The computational cost time obtained with the Graphical Hardware technology, GPU, is compared against Single-Core (sequential) and Multi-Core (parallel) CPU implementations. The GPU implementation allows to reduce the computational cost time in two orders of magnitude.
•A GPU implementation of a FV method for geophysical shallow flows is presented.•The GPU implementation has been performed over unstructured meshes.•The GPU implementation allows to reduce in two orders of magnitude the computational cost.•Real and up-to-date environmental problems are now affordable without the necessity of using coarse meshes.
Among the geophysical surface processes, mud and debris flows show one of the most complex and challenging behaviour for scientists and modellers. These flows consist of highly-unsteady ...gravity-driven movements of water-sediment mixtures with non-Newtonian rheology where the solid concentration could be about 40%–80% of the flow volume and which occur along steep and irregular terrains. Furthermore, the appearance of dynamic pressures in the fluid filling the intergranular pores increases the complexity and dominates the behaviour of the fluidized water-sediment material, leading to the appearance of significant density gradients during the movement. The dynamic pressure in the pore-fluid changes the effective normal stress within the mobilized material, affecting the frictional shear stress between grains and leading to the solid phase dilation/contraction. This must be properly accounted for when developing realistic models for water-sediment surface flows. In this work, a novel physically-based approach for modelling multi-grain dense-packed water-sediment flows is presented. A novel closure formulation for the pressure distribution within the pore-fluid during the movement of dense-packed water-sediment materials has been derived. This closure allows to relate the appearance of shear-induced dynamic pore pressures to the contractive/dilative behaviour of the solid aggregate. The resultant system of depth-averaged conservation laws includes continuity of the density-variable water-sediment material and the different solid classes transported in the flow, as well as the linear momentum equation for the fluidized bulk material, and it is solved using a well-balanced fully-coupled Finite Volume (FV) method. The resultant simulation tool is faced to synthetic, laboratory and real-scale benchmark cases to test its robustness and accuracy. The presence of dynamic pore pressures within the pore-fluid leads to the appearance of a deviatoric contribution to the solid flux, which causes the shear-induced separation of the solid and liquid phases and sustains the flow mobility for long distances, as it has been observed in real mud and debris events.
•The shearing of the solid aggregate generates non-hydrostatic pressures in the pore fluid.•The pore pressure excess affects the basal frictional stress and enhances the flow mobility.•The horizontal pore pressure gradients lead to the separation of the liquid and solid phases.•High solid concentration regions appear within the flow due to the migration of the pore fluid.
•Fully-coupled and decoupled numerical strategies for the 2D bedload transport system are compared.•New approximated Riemann solvers based on the Roe approach have been developed for both coupled and ...decoupled resolution.•Decoupled strategies can only guarantee non-oscillatory results when the bed-flow interaction is very small.•For highly erosive flows, the fully-coupled scheme demonstrates to be more efficient in terms of computational effort.
The bedload transport system of equations, composed by the two-dimensional shallow water equations for the free surface flow motion and the 2D Exner or bedload transport equation for the erodible bed layer, is used for a wide range of sediment transport processes in environmental surface flows. In this work, the numerical resolution has been implemented using improved and efficient versions of two different strategies for combining the hydrodynamical and morphodynamical components of the system. The first strategy is based on the full coupling of the flow and bedload transport equations (FCM), leading to a new formulation for the intercell numerical fluxes which includes the bed elevation into the resolution of the approximated local Riemann problem (RP) at the edges. The stability region of this method is controlled by the eigenvalues of the coupled Jacobian matrix at each intercell edge. On the second hand, an alternative decoupled strategy is considered based on solving independently the shallow water and the bed transport equations at each time step but controlling the stability region by means of an approximation of the coupled Jacobian matrix eigenvalues. This method, called approximate-coupled (ACM) allows simpler expressions for the numerical fluxes at the edges and ensures the stability of the scheme. Both strategies are based on the Finite Volume (FV) method using Roe’s approach for the computation of the numerical fluxes between neighbouring cells and have been implemented into the same CPU-based numerical kernel in order to perform a realistic comparison of the range of applicability and computational efficiency. The ACM can only guarantee non-oscillatory results when the bed-flow interaction factor is small G≤O(10−3). If the interaction factor G is medium or high, G>O(10−2), the decoupled scheme loses its accuracy and robustness. Furthermore, for highly erosive flows the FCM scheme demonstrates to be more efficient in terms of computational effort than the ACM, one of the key points for large-scale and long-term bedload transport realistic applications.
•A coupled 1D–2D shallow water model for irregular geometries is proposed.•The fully conservation property is guaranteed in the coupled model.•Level-volume tables and left/right overflow levels are ...required.•The coupled model is applied to a realistic configuration in the Tiber river.
Coupled 1D–2D numerical strategies are presented in this work for their application to fast computation of large rivers flooding. Both 1D and 2D models are built using explicit upwind finite volume schemes, able to deal with wetting-drying fronts. The topography representation is described via cross sections for the 1D model and with quadrilateral/triangular structured/unstructured meshes for the 2D model. The coupling strategies, free of hydraulic structures and tuning parameters, are firstly validated in a laboratory test dealing with a levee break and its flooding into a lateral plane. The numerical results are compared with a fully 2D model as well as with measurements in some gauge points giving satisfactory results. The simulation of a real flooding scenario in the Tiber river near the urban area of Rome (Italy) is then performed. A lateral coupling configuration is provided, in which the flood wave propagation in the main channel is simulated by means of a 1D model and the inundation of the riverside is simulated by means of a 2D model. On the other hand, a frontal coupling, in which the flood wave is simulated in a 1D model first and then it is propagated into a 2D model, is also performed. The flooding extension is almost well captured by all the schemes presented, being the 1D–2D lateral configuration the most confident with speed-ups of around 15x.
•Coupled Roe’s scheme for SW-Exner equations in cross-section averaged erosive flows.•Explicit expressions for eigenvalues, eigenvectors, wave and source strengths.•A new parameter cb related to the ...bed change appears in the coupled Jacobian matrix.•cb depends on the erosion-deposition mechanism selected to update the cross-section.•Analytical expression for the equilibrium bed slope in variable width rectangular channels.
This work is focused on a numerical finite volume scheme for the coupled shallow water-Exner system in 1D applications with arbitrary geometry. The mathematical expressions modeling the hydrodynamic and morphodynamic components of the physical phenomenon are treated to deal with cross-section shape variations and empirical solid discharge estimations. The resulting coupled equations can be rewritten as a non-conservative hyperbolic system with three moving waves and one stationary wave to account for the source terms discretization. Moreover, the wave celerities for the coupled morpho-hydrodyamical system depend on the erosion-deposition mechanism selected to update the channel cross-section profile. This influence is incorporated into the system solution by means of a new parameter related to the channel bottom variation celerity. Special interest is put to show that, even for the simplest solid transport models as the Grass law, to find a linearized Jacobian matrix of the system can be a challenge in presence of arbitrary shape channels. In this paper a numerical finite volume scheme is proposed, based on an augmented Roe solver, first order accurate in time and space, dealing with solid transport flux variations caused by the channel geometry changes. Channel cross-section variations lead to the appearance of a new solid flux source term which should be discretized properly. The stability region is controlled by wave celerities together with a proper reconstruction of the approximate local Riemann problem solution, enforcing positive values for the intermediate states of the conserved variables. Comparison of the numerical results for several analytical and experimental cases demonstrates the effectiveness, exact well-balancedness and accuracy of the scheme.
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