FD-LBM Simulation of thermosolutal convection generated in an inclined enclosure in the presence of Soret and Dufour effects

International Conference on Materials and Energy (ICOME), La Rochelle, FRANCE, MAY 17-20, 2016International audienceAn hybrid Lattice-Boltzman finite-difference method is proposed to assess the impact of the inclination angle of the cavity on thermosolutal natural convection of a binary fluid confined in a square cavity differentially heated and salted from two opposite walls with constant temperatures and concentrations. This method seems more flexible in implementing additional effects and apparently more efficient than the classical CFD methods. The study is conducted in the case of aiding buoyancy forces and many other controlling parameters. Results obtained showed important qualitative and quantitative effects of the governing parameters on fluid flow and heat and mass transfer characteristics. The heatlines and masslines concepts are also implemented to obtain additional details on heat and mass transfer processes. (C) 2017 The Authors. Published by Elsevier Ltd

Direct carbon fuel cell simulation using hybrid lb-fv approach: effect of carbon fuel specific surface area

In the present study, the simulation of the direct carbon fuel cell (DCFC) using a hybrid Lattice Boltzmann and finite volume approach is performed. The numerical model was first validated against available experimental data. Parametric studies were carried out to investigate the effect of the microstructure of the carbon fuel on the DCFC performance. The increase of the specific surface area (SSA) or porosity was found to minimize the voltage drop in the cell and ameliorate its output power densit

Hybrid lattice Boltzmann finite difference simulation of Soret convection flows in a square cavity with internal heat generation

International audienceThermosolutal natural convection heat and mass transfer in a 2D square cavity are studied numerically in the presence of Soret effect and uniform volumetric heat generation. A hybrid scheme with simple relaxation time lattice Boltzmann method (SRT-LBM) is used to obtain the velocity field while the temperature and concentration fields are deduced from energy and species balances using a finite difference method (FDM). The study focuses on the effect of three parameters, which are the Soret parameter (Sr = -0.5, 0, and 0.5), the buoyancy ratio (N = -1 and 1), and the internal to external Rayleigh numbers ratio (0 <= R <= 80). Combined effects of these parameters on fluid flow and heat and mass transfer characteristics are examined for Lewis number Le = 2, Prandtl number Pr = 0.71, and external Rayleigh number Ra-E = 10(5). The interaction between the heat generation and the thermodiffusion may play an important role in purifying/charging the confined fluid from/with species by considering positive/negative values of Sr

The Helicity Sign of Flux Transfer Event Flux Ropes and Its Relationship to the Guide Field and Hall Physics in Magnetic Reconnection at the Magnetopause

International audienceAbstract Flux Transfer Events (FTEs) are transient magnetic flux ropes typically found at the Earth's magnetopause on the dayside. While it is known that FTEs are generated by magnetic reconnection, it remains unclear how the details of magnetic reconnection controls their properties. A recent study showed that the helicity sign of FTEs positively correlates with the east‐west ( B y ) component of the Interplanetary Magnetic Field (IMF). With data from the Cluster and Magnetospheric Multiscale missions, we performed a statistical study of 166 quasi force‐free FTEs. We focus on their helicity sign and possible association with upstream solar wind conditions and local magnetic reconnection properties. Using both in situ data and magnetic shear modeling, we find that FTEs whose helicity sign corresponds to the IMF B y are associated with moderate magnetic shears while those that do not correspond to the IMF B y are associated with higher magnetic shears. While uncertainty in IMF propagation to the magnetopause may lead to randomness in the determination of the flux rope core field and helicity, we rather propose that for small IMF B y , which corresponds to high shear and low guide field, the Hall pattern of magnetic reconnection determines the FTE core field and helicity sign. In that context we explain how the temporal sequence of multiple X‐line formation and the reconnection rate are important in determining the flux rope helicity sign. This work highlights a fundamental connection between kinetic processes at work in magnetic reconnection and the macroscale structure of FTEs