Entropy Stable Finite Volume Approximations for Ideal Magnetohydrodynamics

This article serves as a summary outlining the mathematical entropy analysis of the ideal magnetohydrodynamic (MHD) equations. We select the ideal MHD equations as they are particularly useful for mathematically modeling a wide variety of magnetized fluids. In order to be self-contained we first motivate the physical properties of a magnetic fluid and how it should behave under the laws of thermodynamics. Next, we introduce a mathematical model built from hyperbolic partial differential equations (PDEs) that translate physical laws into mathematical equations. After an overview of the continuous analysis, we thoroughly describe the derivation of a numerical approximation of the ideal MHD system that remains consistent to the continuous thermodynamic principles. The derivation of the method and the theorems contained within serve as the bulk of the review article. We demonstrate that the derived numerical approximation retains the correct entropic properties of the continuous model and show its applicability to a variety of standard numerical test cases for MHD schemes. We close with our conclusions and a brief discussion on future work in the area of entropy consistent numerical methods and the modeling of plasmas

A very cool brown dwarf in UKIDSS DR1

The definitive version is available at www.blackwell-synergy.com. Copyright Blackwell Publishing DOI : 10.1111/j.1365-2966.2007.12348.xPeer reviewe

Shape Sensitivity of Free-Surface Interfaces Using a Level Set Methodology

In this paper we develop the continuous adjoint methodology to compute shape sensitivities in free-surface hydrodynamic design problems using the incompressible Euler equations and the level set methodology. The identification of the free-surface requires the convection of the level set variable and, in this work, this equation is introduced in the entire shape design methodology. On the other hand, an alternative continuous adjoint formulation based in the jump condition across the interface, and an internal adjoint boundary condition is also presented. It is important to highlight that this new methodology will allow the specific design of the free-surface interface, which has a great potential in problems where the target is to reduce the wave energy (ship design), or increase the size of the wave (surfing wave pools). The complete continuous adjoint derivation, the description of the numerical methods (including a new high order numerical centered scheme), and numerical tests are detailed in this paper. I

Eight new T4.5-T7.5 dwarfs discovered in the UKIDSS large area survey data release 1

The definitive version is available at www.blackwell-synergy.com Copyright Blackwell Publishing DOI : 10.1111/j.1365-2966.2007.12023.xPeer reviewe