Numerical solution of the nonlinear Schrodinger equation using smoothed-particle hydrodynamics

We formulate a smoothed-particle hydrodynamics numerical method, traditionally used for the Euler equations for fluid dynamics in the context of astrophysical simulations, to solve the nonlinear Schrodinger equation in the Madelung formulation. The probability density of the wave function is discretized into moving particles, whose properties are smoothed by a kernel function. The traditional fluid pressure is replaced by a quantum pressure tensor, for which a robust discretization is found.

Rayleigh-Bénard instability in graphene

Motivated by the observation that electrons in graphene, in the hydrodynamic regime of transport, can be treated as a two-dimensional ultrarelativistic gas with very low shear viscosity, we examine the existence of the Rayleigh-Bénard instability in a massless electron-hole plasma. First, we perform a linear stability analysis, derive the leading contributions to the relativistic Rayleigh number, and calculate the critical value above which the instability develops.

A hierarchical Krylov--Bayes iterative inverse solver for MEG with physiological preconditioning

The inverse problem of MEG aims at estimating electromagnetic cerebral activity from measurements of the magnetic fields outside the head. After formulating the problem within the Bayesian framework, a hierarchical conditionally Gaussian prior model is introduced, including a physiologically inspired prior model that takes into account the preferred directions of the source currents. The hyperparameter vector consists of prior variances of the dipole moments, assumed to follow a non-conjugate gamma distribution with variable scaling and shape parameters.

Lattice Boltzmann simulations of vortex entrapment of particles in a microchannel with curved or flat edges

Numerical simulations were conducted to determine the effects of flat-edge and curved-edge channel wall obstacles on the vortex entrapment of uniform-size particles in a microchannel with a T-shape divergent flow zone at different flow Reynolds numbers (Re). Two-particle simulations with a non-pulsating flow indicated that although particles were consistently entrapped in a vortex zone in a microchannel with flat-edge wall obstacles at all Re studied, vortex zone entrapment of particles occurred only at the lowest Re in a microchannel with curved-edge wall obstacles.

A multispeed Discrete Boltzmann Model for transcritical 2D shallow water flows

In this work a Discrete Boltzmann Model for the solution of transcritical 2D shallow water flows is presented and validated. In order to provide the model with transcritical capabilities, a particular multispeed velocity set has been employed for the discretization of the Boltzmann equation. It is shown that this particular set naturally yields a simple and closed procedure to determine higher order equilibrium distribution functions needed to simulate transcritical flow.