In modern electron devices, because of the presence of very high and rapidly varying electric fields, phenomena occur which cannot be described by means of the standard drift-diffusion (DD) models. For example, impact ionization and heat generation in the bulk material.
Therefore generalizations of the DD equations have been sought which incorporate more dynamical variables, particularly the carrier energy.
This has lead to the so-called energy-transport and hydrodynamical models. Here we present a new hydrodynamical model recently proposed by Anile, Liotta and Mascali (ALM model) in which the closure of the equations is obtained in sytematic and rational way. In fact it is based on an asymptotic solution for high fields of the Boltzmann transport equation (BTE) for semiconductors recently found by Liotta and Majorana and
therefore it is not necessary to assume phenomenological closures or ad hoc expressions for the productions terms. All the parameters appearing in the model are explicitly calculated for a simple parabolic band silicon model  in terms of the acoustic and optical phonon interactions constants.
From the mathematical viewpoint the resulting model is strictly hyperbolic. Therefore numerical methods suitable for hyperbolic systems of
conservation laws have been used, completed with suitable splitting strategies. We have tested the new model both in one and two dimensional
physical situations. In particular we have considered the proposed model in the cases of bulk silicon, 1 - D ballistic diode n+ - n  - n+  and
two-dimensional MESFET. Comparisons have been made with the popular Blotekjaer-Baccarani Wordemanhydrodynamical model (BBW model), Stratton energy-transport model and Monte-Carlo simulations.