Configuration File

Runtime parameters are passed to FlowEDG through a configuration file named FlowEDG.config which must be located in the current working directory. FlowEDG.config reads groups of parameters, called parameter lists. Currently there are six available parameter lists:

1. Project
2. EquationParameters
3. NonlinearSolverParameters
4. LinearSolverParameters
5. UnsteadyParameters
6. PostProcessingParameters

Parameter lists begin with the parameter list name and enclose the list options in brackets. Comments are designated by a '#' and can be placed anywhere in the configuration file. The parameter name and value is always separated by an equal sign, and the assignment is terminated with a semicolon. White space should not matter.

The list of currently supported variables along with their permissible values (in parentheses) and default value are listed below for each parameter list.

Project

• Name (default = ) -- Name of the project.

• Equation (default = Euler, Navier-Stokes) -- Specify which governing equation to solve. Currently, the only two supported options are Euler and Navier-Stokes.

• MeshFile (default = ) -- Name of the GMSH mesh file.

• Discretization (default = EDG, HDG) -- Specifies whether to use EDG or HDG discretization. Generally, it is best to use EDG for p < 4 and HDG for p>= 4.

• OptimizedNodeSpacing (default = true) -- Specifies whether or not the specified mesh uses optimized node spacing (see the MeshOpt wiki for more details).

EquationParameters

• gamma (default = 1.4) -- ratio of specific heats
• Pr (default = 0.72) -- Prandtl number
• Re (default = 1000) -- Reynold's number
• M_inf (default = 0.3) -- Freestream Mach number
• U_inf (default = {1,0,0}) -- Unit freestream velocity vector (magnitude must be 1).

NonlinearSolverParameters

• Type (default = Quasi-Newton, Newton) -- Which non-linear solver to use. Quasi-Newton does not update the Jacobian every time step, while Newton does.
• MaxIt (default = 1000) -- Maximum number of iterations.
• RelTol (default = 1.0e-8) -- The tolerance for Newton's method, normalized by the initial residual norm.
• MinStep (default = 1.0e-3) -- The minimum allowable search length. If Newton does not converge using this length, the solver will terminate.

LinearSolverParameters

• Method (default = GMRES) -- The linear solver algorithm to use. The only currently supported algorithm is GMRES.
• RelTol (default = 1.0e-4) -- The relative tolerance to which the linear system is solved.
• Orthog (default = ICGS, DGKS) -- The type of orthogonalization strategy for GMRES to use.
• MaxIt (default = 1000) -- The maximum number of total iterations allowed (including restarts).
• Restart (default = 500) -- The GMRES orthogonalization will restart every Restart iterations.
• MaxRestarts (default = 20) -- The maximum number of restarts.

UnsteadyParameters

• SolveUnsteady (default = false) -- Tells the solver to solve the unsteady equations, as opposed to steady-state.
• dt (default = 0.01) -- The time step to be used for temporal integration
• Nt (default = 1000) -- The number of time steps to be taken.
• Integration (default = DIRK33, DIRK22, DIRK11) -- The time integration algorithm to implement.
• Restart (default = false) -- Specifies whether or not to restart the solution from a restart file.
• RestartTimestep (default = 0) -- The time step from which the solution will be restarted.

PostProcessingParameters

• ValuesToSave (default = ,rho,M,c,s,p,|Vort|,|V|,V,Vort) -- Specifies which quantities to compute and write to a post-processing file. Currently, the only supported post-processing format is VTK's .pvtu standard.
• OutputDirectory (default = ) -- The directory where the post-processing files will be written to. All state files will be be named according to the following pseudo c-code: dgsolution_timestep%06d_proc_%06d.vtu. In other words, post-processing files will indicate their time step and processor ID, padded with six zeros and will be written in VTK's .vtu format.
• NRefinements (default = 2) -- The number of subdivisions to perform on each element. FlowEDG visualizes high-order elements by uniformly refining them NRefinement times. Be careful about setting NRefinement too large. If NRefinement=4 and your mesh is composed of tets, 8^4=4096 tets will be created for each element in your high order mesh!.
• PostProcessOnly (default = false) -- Specifies that the solver is to be run in post-processing mode. In this mode, the solver does not solve the governing equation, it just evaluates the post-processing values of interest and saves them to the disk.
• StartTimestep (default = 0) -- Only used when PostProcessOnly = true. Specifies the time step for which to start the post-processing.
• NTimesteps (default= 1) -- Only used when PostyProcessOnly = true. Specifies how many time steps to post-process, starting with StartTimestep.