Numerical Simulation Of Magnetohydrodynamic Turbulent Flows

The study of magnetohydrodynamic (MHD) flows in presence of intense magnetic fields isfundamentalimportance for the development of nuclear fusion reactors. In the blanket of the fusionreaction blanket are used for producing tritium that feeds the fusion reaction, for removing thegenerated heat and for shielding the neutron and radiation fluxes. The magnetic field that confinesthe fusion plasma in the blanket, the metal flow of fluid under a magnetic field will cause themagnetohydrodynamic effect (MHD effect) in the blanket, MHD effect modifies stream patterns,flow features and pressure distribution, Liquid metal MHD flow research are closely related withmetallurgy, nuclear fusion which are a lot of advenced science and technology. Because he metalflow of fluid under a magnetic field in the blanket, it will cause induced current,the induced currentunder the magnetic field will cause the Lorenz force, the direction is in contrast to the flow direction,it will affects the flow velocity.There are two kinds of different boundary layer in duct flow:Hartmann layer and Boundary layer, two layer are very thin, but its current density will very large,so the layer will divide a certain number of grid, thus this study of the numerical simulationcomputation is greatly increased.In recent years, the numerical simulation research of the metal fluid MHD flow in the blankethas made great development, and focus in the study of people also from laminar graduallytransferred to the more common in nature and engineering on the turbulence model. Turbulenceis a kind of complex flow in nature, but people in the study of the mechanism of turbulence andMHD turbulence numerical simulation method are still in the exploratory stage. Large eddysimulation method is adopted in this paper to the simulation MHD turbulence.We use open source CFD oftware OpenFOAM developed suitable for the study of this thesisMHD turbulence MHD solver, first we verify our MHD solver’s correctness. With the developmentof MHD solver for different examples of numerical calculation, as the calculation of the ongoing,we can see section velocity of the fluid continuously pressing trends, center velocity drop and thevelocity near the wall up. We observed the velocity contours and the velocity vector in thecross-section of the duct square, we can see that turbulent flow in the duct flow is the vortices, invertical direction it have a magnetic field, the magnetic field had a flat trend for speed, accordinglyeddy current flow also reduce, the velocity vector move to the corners and the corner near thehartmann layer. Through Y+=15near the wall of the transient speed we can clearly see theturbulent fluid of high speed and low speed region, combined with y direction magnetic field, theturbulence of high speed and low speed will be stretched along the flow direction. We simulatethe different examples, compared the speed curve contrast of Reynolds number Re=4300, Re= 5300, and the hartmann number Ha=23, through average velocity and fluctuation velocity contrastwe can see large Reynolds number affected on the MHD turbulence liquid is obvious, andturbulence intensity is bigger. Compared the Reynolds number Re=5300, hartmann number23, HaHa==46respectively the average velocity and fluctuation velocity contrast, through the contrastcan be found that the stronger the magnetic field, the greater the hartmann number for MHDturbulence had a stronger suppression effect.