Search results for "Advection"
showing 10 items of 61 documents
MAST solution of advection problems in irrotational flow fields
2007
Abstract A new numerical–analytical Eulerian procedure is proposed for the solution of convection-dominated problems in the case of existing scalar potential of the flow field. The methodology is based on the conservation inside each computational elements of the 0th and 1st order effective spatial moments of the advected variable. This leads to a set of small ODE systems solved sequentially, one element after the other over all the computational domain, according to a MArching in Space and Time technique. The proposed procedure shows the following advantages: (1) it guarantees the local and global mass balance; (2) it is unconditionally stable with respect to the Courant number, (3) the so…
Texture advection on discontinuous flows
2015
Texture advection techniques, which transport textures using a velocity field, are used to visualize the dynamics of a flow on a triangle mesh. Some flow phenomena lead to velocity fields with discontinuities that cause the deformation of the texture which is not properly controlled by these techniques. We propose a method to detect and visualize discontinuities on a flow, keeping consistent texture advection at both sides of the discontinuity. The method handles the possibility that the discontinuity travels across the domain of the flow with arbitrary velocity, estimating its speed with least-squares approximation. The technique is tested with different sample scenarios and with two avala…
The Domuyo volcanic system: An enormous geothermal resource in Argentine Patagonia
2014
Fil: Chiodini, Giovanni. Istituto Nazionale Di Geofisica E Vulcanologia. Italia. Fil: Liccioli, Caterina. Universidad Nacional de Rio Negro. Instituto de Investigaciones en Paleobiologia y Geologia; Argentina. Río Negro, Argentina Fil: Vaselli, Orlando. Universita Degli Studi Di Firenze; Italia Fil: Calabrese, Sergio. Università di Palermo; Italia Fil: Tassi, Franco. Universita Degli Studi Di Firenze; Italia Fil: Caliro, Stefano. Istituto Nazionale Di Geofisica E Vulcanologia; Italia Fil: Caselli, Alberto Tomás Universidad Nacional de Rio Negro. Instituto de Investigaciones en Paleobiologia y Geologia; Argentina. Río Negro, Argentina Fil: Agusto, Mariano R. Universidad de Buenos Aires. Facu…
Detecting the chaotic nature of advection in complex river flows
2012
In order to detect signatures of chaotic advection in river surface motion, surface buoys equipped with GPS were deployed in a field experiment in River Danube, Hungary. The buoys were released in the vicinity of groynes where complex mixing processes occur. A detailed analysis of the trajectories was carried out, focusing on the time evolution of the distance between buoy pairs. The analysis included the determination and comparison of local Lyapunov exponents and prediction times of finite-time hyperbolic behaviour, which is related to strong mixing. Despite of the small number of applied buoys we found evidence on Lagrangian chaos in the wake of a groyne field. In order to supplement the…
Core-collapse supernova simulations in one and two dimensions: comparison of codes and approximations
2018
We present spherically symmetric (1D) and axisymmetric (2D) supernova simulations for a convection-dominated 9 Msun and a 20 Msun progenitor that develops violent activity by the standing-accretion-shock instability (SASI). We compare in detail the Aenus-Alcar code, which uses fully multidimensional two-moment neutrino transport with an M1 closure, with a ray-by-ray-plus (RbR+) version of this code and with the Prometheus-Vertex code that employs RbR+ two-moment transport with a Boltzmann closure. Besides testing consequences of ignored non-radial neutrino-flux components in the RbR+ approximation, we also discuss the influence of various transport ingredients applied or not applied in rece…
The jets and disc of SS 433 at super-Eddington luminosities
2009
We examine the jets and the disc of SS 433 at super-Eddington luminosities with 600 times Eddington critical accretion rate by time-dependent two-dimensional radiation hydrodynamical calculations, assuming alpha-model for the viscosity. One-dimensional supercritical accretion disc models with mass loss or advection are used as the initial configurations of the disc. As a result, from the initial advective disc models with alpha =0.001 and 0.1, we obtain the total luminosities 2.5x10^{40} and 2.0x10^{40} erg/s. The total mass-outflow rates are 4x10^{-5} and 10^{-4} solar-mass/yr and the rates of the relativistic axial outflows in a small half opening angle of 1 degree are about 10^{-6} solar…
Accumulation of low oxygen water in deep waters of ice-covered lakes cooled below 4 °C
2013
We studied vertical distribution of oxygen under the ice of 5 medium-sized, morphologically variable lakes that cooled well below 4 °C before freezing. In the upper part of the water column, dissolved oxygen and dissolved inorganic carbon concentrations generally remained vertically almost uniform, but in the deepest water, concentrations changed rapidly near the bottom. The coincidence of the changes with an increase in deep water temperature shows that they were due to advection of water made heavier by the heat flux from the sediment. Consequently, water with low concentrations of dissolved oxygen and high concentrations of dissolved inorganic carbon accumulated in the deepest part of th…
Impacts of soil moisture content on simulated mesoscale circulations during the summer over eastern Spain
2015
Abstract The Regional Atmospheric Modeling System (RAMS) version 6.0 has been used to investigate the impact and influence of initial soil moisture distributions on mesoscale circulations. To do this, two different events have been selected from the 2011 summer season: one at the beginning of the season (June) and the other one at the end of the season (August). For each of these mesoscale frameworks a total of five distinct simulations were performed varying the initial soil moisture content: a control run and four additional sensitivity tests. The control run, corresponding to a low soil moisture content, is the one used within the real-time weather forecasting system implemented in the V…
A Flux Method for the Numerical Solution of the Stochastic Collection Equation
1998
Abstract A new mass conservative flux method is presented for the numerical solution of the stochastic collection equation. The method consists of a two-step procedure. In the first step the mass distribution of drops with mass x′ that have been newly formed in a collision process is entirely added to grid box k of the numerical grid mesh with xk ⩽ x′ ⩽ xk+1. In the second step a certain fraction of the water mass in grid box k is transported to k + 1. This transport is done by means of an advection procedure. Different numerical test runs are presented in which the proposed method is compared with the Berry–Reinhardt scheme. These tests show a very good agreement between the two approaches…
RAMS-forecasts comparison of typical summer atmospheric conditions over the Western Mediterranean coast
2014
Abstract The Regional Atmospheric Modeling System (RAMS) has been used in order to perform a high-resolution numerical simulation of two meteorological events related to the most common atmospheric environments during the summer over the Western Mediterranean coast: mesoscale circulations and western synoptic advections. In this regard, we take advantage of the operational RAMS configuration running within the real-time forecasting system environment already implemented over this Mediterranean area, precisely in the Valencia Region and nearby areas. The attention of this paper is especially focused on identifying the main features of both events and the ability of the model in resolving the…