Entropy Balance and Dispersive Oscillations in Lattice Boltzmann Models

We conduct an investigation into the dispersive post-shock oscillations in the entropic lattice-Boltzmann method (ELBM). To this end we use a root finding algorithm to implement the ELBM which displays fast cubic convergence and guaranties the proper sign of dissipation. The resulting simulation on the one-dimensional shock tube shows no benefit in terms of regularization from using the ELBM over the standard LBGK method. We also conduct an experiment investigating of the LBGK method using median filtering at a single point per time step. Here we observe that significant regularization can be achieved.Comment: 18 pages, 4 figures; 13/07/2009 Matlab code added to appendi

Possibility and Impossibility of the Entropy Balance in Lattice Boltzmann Collisions

We demonstrate that in the space of distributions operated on by lattice Boltzmann methods that there exists a vicinity of the equilibrium where collisions with entropy balance are possible and, at the same time, there exist an area of nonequilibrium distributions where such collisions are impossible. We calculate and graphically represent these areas for some simple entropic equilibria using single relaxation time models. Therefore it is shown that the definition of an entropic LBM is incomplete without a strategy to deal with certain highly nonequilibrium states. Such strategies should be explicitly stated as they may result in the production of additional entropy.Comment: v2 minor misprint correction

School-based indicated prevention interventions for anxiety in children and adolescents: a commentary on a systematic review

Mental health problems such as anxiety are on the increase in children and adolescents. However, rising demand and cuts to mental health services make it difficult for young people to access the support they need. School-based interventions aimed at preventing or reducing anxiety have the potential to provide help to large numbers of children and adolescents. However, the effectiveness of these interventions for different groups is somewhat unclear. This commentary summarises and critically appraises a recent systematic review which investigated the effectiveness of school-based interventions to prevent and reduce anxiety symptoms in indicated groups of children and adolescents