1,720,987 research outputs found
A lattice Boltzmann approach for immiscible fluids with very different viscosities
No full textIn this article, a lattice Boltzmann model for two immiscible fluids with same density
but a large viscosity difference is developed. The effect of surface tension is included.
An indicator function is used to model the interface motion and is updated by a lattice
Boltzmann scheme. The macroscopic equation for this function is derived using multiscale
analysis. Numerical results are compared with theoretical and experimental ones
for the problem of drop deformation under steady linear flows. A qualitative comparison
with results given by a level contour reconstruction method for drop collision in three
dimensions is also shown. Other numerical applications, such as flow past obstacles and
a falling drop, are presented
Metodi di misura dei flussi idrici sotterranei della zona insatura
No full text14ff., 5 tabb.. Pubbl. GNDCI del CNR n. 208
Numerical treatment of a nonlinear nonlocal transport equation modeling crystal precipitation
No full textNumerical methods to solve certain nonlinear nonlocal transport equations (hyperbolic partial differential equations with smooth solutions), even singular at the boundary, are developed and analyzed. As a typical case, a model equation used to describe certain crystal precipitation phenomena (a slight variant of the so-called Lifshitz-Slyozov-Wagner model) is considered. Choosing a train of few delta functions as initial crystal size distribution, one can model the technologically important case of having only a modest
number of crystal sizes. This leads to the reduction of the transport equation to a system of ordinary differential equations, and suggests a new method of
solution for the transport equation, based on Shannon sampling, which is widely used in communication theory
La professione sanitaria del tecnico di neurofisiopatologia: formazione, profilo professionale, ambiti di attività
No full textNumerical solution of certain classes of transport equations in any dimension by Shannon sampling
No full textA method is developed for computing solutions to some class of linear and nonlinear transport equations (hyperbolic partial differential equations with smooth solutions), in any dimension, which exploits Shannon sampling, widely used in information theory and signal processing. The method
can be considered a spectral or a wavelet method, strictly related to the existence of characteristics, but allows, in addition, for some precise error estimates in the reconstruction of continuous profiles from discrete data.
Non-dissipativity and (in some case) parallelizability are other features of this approach. Monotonicity-preserving cubic splines are used to handle nonuniform sampling. Several numerical examples, in dimension one or two, pertaining to single linear and nonlinear (integro-differential) equations, as well as to certain systems, are given
Ground-state computation of Bose-Einstein condensates by an imaginary-time quantum lattice Boltzmann scheme
No full textThe multidimensional formulation of the quantum lattice Boltzmann (qLB) scheme is extended to the case of nonlinear quantum wave equations. More specifically, imaginary-time formulations of the qLB scheme are developed and applied to the numerical computation of the ground state of the Gross-Pitaevskii equation in one and two spatial dimensions. The calculation is validated through detailed comparison with other numerical methods, as well as with analytical results based on the Thomas-Fermi approximation. The linear scaling of the time-step size with the spatial mesh spacing, a distinctive feature of the present quantum kinetic approach, is also numerically demonstrated
Correction: Groundwater circulation and earthquake-related changes in hydrogeological karst environments: a case study of the Sibillini Mountains (central Italy) involving artificial tracers (Hydrogeology Journal, (2020), 28, 7, (2409-2428), 10.1007/s10040-020-02207-w) [Correction]
No full textThe article “Groundwater circulation and earthquake-related changes in hydrogeological karst environments: a case study of the Sibillini Mountains (central Italy) involving artificial tracers”, written by T. Nanni, P. M.Vivalda, S. Palpacelli,M.Marcellini and A. Tazioli, was originally published electronically on the publisher’s internet portal on 21 July 2020 without open access. With the author(s)’ decision to opt forOpen Choice the copyright of the article changed on 13 August 2020 to © The Author(s) 2020 and the article is forthwith distributed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http:// creativecommons.org/licenses/by/4.0. The original article has been corrected
Monitoring and modelling interactions between the montagna dei fiori aquifer and the castellano stream (Central Apennines, Italy)
Full text linkGroundwater is the most used water resource around the world, but due to population growth and climate change the alluvial lowland aquifers are often polluted and over-exploited. Thus, more and more frequently water managers need to shift their attention to mountain regions to identify groundwater resources for drinking purposes. This study presents a monitoring and modelling approach that allowed to quantify the inflow from the "Montagna dei Fiori" fractured aquifer to the Castellano stream. Continuous monitoring of flow discharge and temperature during an entire hydrological year (2018-2019) at two monitoring stations along the stream allowed to discriminate between the baseflow (on average, 0.891 m3/s) and the run-off (on average, 0.148 m3/s) components. A hydrogeological basin-wide numerical flow model (using MODFLOW-2005) was set up using information from hydrogeological and geomechanical surveys. The model was calibrated using the daily baseflow observations made in the Castellano stream (R2 = 0.75). The calibrated model allowed to quantify groundwater/surface water interactions. After an automated sensitivity analysis (using MODFLOW-2000), the recharge was found to be the most uncertain parameter, followed by the hydraulic conductivity zonation. This methodology could be applied in other mountain regions where groundwater monitoring networks are usually lacking to improve water resources management
Estimation of saturated hydraulic conductivities in a large tank experiment by modelling of different pedotransfer functions
No full text
- …
