Search results for "numerical [Methods]"
showing 10 items of 500 documents
The MAST-edge centred lumped scheme for the flow simulation in variably saturated heterogeneous porous media
2012
A novel methodology is proposed for the solution of the flow equation in a variably saturated heterogeneous porous medium. The computational domain is descretized using triangular meshes and the governing PDEs are discretized using a lumped in the edge centres numerical technique. The dependent unknown variable of the problem is the piezometric head. A fractional time step methodology is applied for the solution of the original system, solving consecutively a prediction and a correction problem. A scalar potential of the flow field exists and in the prediction step a MArching in Space and Time (MAST) formulation is applied for the sequential solution of the Ordinary Differential Equation of…
Simulation of Sediment transport and flow characteristics downstream of a hydraulic structure
2016
The presence of a hydraulic structure (such as a dam) in a given river reach determines “constrained” sediment boundary conditions and thus transient transport phenomena. Many predictive mobile-bed one-dimensional models have been developed in or-der to predict sediment transport during transients but, even today, they have not attained a high degree of efficacy. This is because these models are confronted with some difficulties such as the reliable prediction of bed roughness or/and to the presence of flexible vegetation, of hydraulic sorting, of water-bed sediment interchanges in no-equilibrium situations. In the present work, with the aid of a 1-D numerical model previously developed (Te…
A marching in space and time (MAST) solver of the shallow water equations. Part II: The 2D model
2007
Abstract A novel methodology for the solution of the 2D shallow water equations is proposed. The algorithm is based on a fractional step decomposition of the original system in (1) a convective prediction, (2) a convective correction, and (3) a diffusive correction step. The convective components are solved using a Marching in Space and Time (MAST) procedure, that solves a sequence of small ODEs systems, one for each computational cell, ordered according to the cell value of a scalar approximated potential. The scalar potential is sought after computing first the minimum of a functional via the solution of a large linear system and then refining locally the optimum search. Model results are…
Grafiska integrēšana un diferencēšana. Neperiodiskas līknes nolīdzinājuma atrašana
1931
Saturs: Funkcionāls sakars, tā attēlošana 3 Empirisks un racionāls nolīdzinājums 3 Pieskares konstrukcijas 6 Grafiska integrēšana 7 Grafiska diferencēšana 9 Līkņu veidi un nolīdzinājumi 10 Līkņu nolīdzinājumi pārveidotā koordinātu sistēmā 11 Deformācija 13 Līkņu pazīmes 13 Atsevišķi nolīdzinājumu veidi 17 Nolīdzinājuma atrašana, ja dots līknes zars 20 Piemēri 21 Nolīdzinājuma atrašana, kad doti līknes visi zari un īpaši punkti 25
High Resolution Dispersion Modeling near Tunnel Exits
1996
This contribution is concerned with a critical problem which usually occurs at motortraffic tunnels within towns. All exhaust gases accumulating along the entire tunnel distance readily leave the tunnel exits in a very concentrated form. Since modern urban traffic management affords more and more tunnel constructions within highly built-up areas, a reliable calculation of the resulting immission distribution in the neighbourhood of tunnel exits is of great importance.
A numerical meshless particle method in solving the magnetoencephalography forward problem
2012
In this paper, a numerical meshless particle method is presented in order to solve the magnetoencephalography forward problem for analyzing the complex activation patterns in the human brain. The forward problem is devoted to compute the scalp potential and magnetic field distribution generated by a set of current sources representing the neural activity, and in this paper, it has been approached by means of the smoothed particle hydrodynamics method suitably handled. The Poisson equation generated by the quasi-stationary Maxwell’s curl equations, by assuming Neumann boundary conditions has been considered, and the current sources have been simulated by current dipoles. The adopted meshless…
Ability of software SWMM to simulate sewer smooth pressurization transient
2010
As a consequence of heavy rainfall events or network malfunctioning, filling of sewers (pressurization) and network overflowing may occur. Several models are commonly used to simulate floods in drainage networks and their results are usually thought to be reliable and robust. Actually, mathematical models based on the momentum equation appear to be more suitable in correctly simulating the pressurization moving jump but models based on the energy equation are much more popular because of their greater simplicity in comparison to the former ones. In this paper, on the basis of laboratory pipe tests, the ability of software SWMM (Storm Water Management Model, probably the most popular softwar…
SPH NUMERICAL MODELLING OF WAVE-STRUCTURE INTERACTION
The present thesis aims at contributing to a better understanding and modelling of flow driven by wave propagation approaching artificial or natural structures. From a physical point of view, a simplistic descrip- tion of the interaction of sea waves with a coastal structure can be given as the result of all processes felt by the waves which, propagating from offshore to nearshore, impact on the structure itself. Indeed, as sea waves approach a shore, the motion they generate deep down begins to interact with the sea bed. This slows the waves down and causes the crests in a series of waves to bunch up; this effect is called shoaling. The period of the waves does not change, but their height…
NUMERICAL SIMULATION OF SEDIMENT RESUSPENSION IN MECHANICALLY STIRRED VESSEL
2008
Numerical simulations of the kinetics of pulsed electron beam induced synthesis of nanogels in dilute aqueous polymer solutions
2018
Nanogel can be produced by irradiation of dilute aqueous polymer solutions. The nanogels are formed primarily through intramolecular radical-radical crosslinking reactions between two polymer radical sites.