Boundary Conditions, Atomic Physics, & Geometry Group Wes Lowrie, Slava Lukin, George Marklin, Eric Meier, Uri Shumlak To capture the complex and, sometimes, asymmetric geometries of innovative/emerging concepts, we will use 3 D-mesh codes. Aerospace & Energetics Research Program Plasma Dynamics Group
Group Objectives Develop computational tools capable of accurately simulating ICC plasmas. Specifically, plasmas that may have neutral/plasma interactions, high speed flows, asymmetric boundaries. l Boundary conditions including electrically conducting & insulating, plasma/gas inflow & outflow, external magnetic fluxes, external circuit l General 3 D geometries – tetrahedral meshes, unstructured hexahedral meshes, or unstructured blocks of structured hexahedral meshes. l Atomic physics (ionization, recombination, charge exchange, radiation) l High speed flows l Equation of state and transport models (SESAME tables or analytical) l Hall effect physics l Verification to test computer implementation; Validation to test physical model through application to experiments Aerospace & Energetics Research Program Plasma Dynamics Group
Task Distribution The approach is to distribute the development tasks among the group members: l Implementation algorithm for self-consistent electric and magnetic boundary conditions: conducting, insulating, potential, combined [Marklin] l Develop MH 4 D as a general test-bed code for implementing boundary conditions, and physical models. [Meier] l Develop finite element code for 3 D-meshes using SEL or SEL algorithm. [Lowrie and Lukin] l Atomic physics – governing equations and implementation: ionization, recombination, charge exchange [Shumlak] l Applications to experiments to test code components. [all] Aerospace & Energetics Research Program Plasma Dynamics Group
SEL Code Today l Fortran 90/95; Efficient parallel operation with MPI and PETSc; l 2 D high order spectral elements: Very low numerical dispersion + Adaptable grid + Parallelization; l Time step: Fully implicit, 2 nd-order accurate, Newton iteration, Static condensation, LU direct or GMRES iterative linear solver with ILU preconditioning within PETSc; l Adaptivity: Robust and automated in time – based on the rate of Newton convergence, and in space – based on spatial convergence error and use of harmonic map generation; l Modular flux-source form: Simple and general problem setup, allows for any relevant multi-fluid Extended MHD system of PDEs + Abundant flexibility in specifying boundary conditions. Thoroughly tested in linear and non-linear regimes against analytics, multiple published simulation results, and other macroscopic modeling codes in single and two-fluid MHD. Aerospace & Energetics Research Program Plasma Dynamics Group
The Future: “SEL” → “ … ” l Already Under Development: Improved preconditioning with FETI-DP and hope of scalability from ≤ 100 to ~1000 or more processors; l First Next Step: Extend the computational grid from a single logically rectangular block to an unstructured collection of structured blocks in 2 D; l Further Developments: – Interface the code with an automatic grid generator; – Transform 2 D structured blocks into 3 D structured blocks; – If necessary, add the capability of unstructured blocks; – Extend “in-house” preconditioning from 2 D to 3 D; – Extend, test and optimize grid adaptation by way of harmonic map generation from 2 D to 3 D. Aerospace & Energetics Research Program Plasma Dynamics Group
Future Plans l Atomic Physics Model – Complete implementation in MH 4 D – Currently static, cold neutral fluid; compare solutions for gas breakdown – Add burn-out of neutral fluid – Include energy transfer between neutral and plasma fluids – Add thermal conduction within the neutral fluid – Allow neutral fluid dynamics, response to pressure gradients (2 nd Fluid) – Perform cold-start simulation of Za. P – Add radiative energy loss models (simple model, ionization state tracking) – Migrate atomic physics to finite element code Aerospace & Energetics Research Program Plasma Dynamics Group
Future Plans l Boundary Conditions – Develop self-consistent boundary condition algorithm – Implement in either MH 4 D, M 4, or FEMLAB code – Validate through application to HIT-SI – Investigate additional boundary conditions, e. g. RMF – Migrate to finite element code l 3 D-Mesh, Finite Element Code – SEL modifications discussed previously, either in SEL or new framework – Decide on mesh generator, e. g. CUBIT – Output format and visualization, e. g. HDF, Vis. It, Tecplot (use work from interface group) l Investigate algorithms to model Hall terms for M 4 and MH 4 D, though may already be addressed by SEL code. l Support the interface group in simulating experiments. Aerospace & Energetics Research Program Plasma Dynamics Group
Скачать презентацию Boundary Conditions Atomic Physics Geometry Group Wes
76b13a2920f0dfc42879474cd28d8224.ppt