The following input files are required to run HyPar. They are indicated as being mandatory or optional. If optional, then default values are used if not found.

Note: It is best to start with the provided examples, understand their input files based on the information on this page, and then modify them to run other cases.

solver.inp

Requirement: mandatory

Read by: ReadInputs()

Description: Specify the main simulation-related parameters.

Format: ASCII text

    begin
        <keyword>   <value>
        <keyword>   <value>
        <keyword>   <value>
        ...
        <keyword>   <value>
    end

where the list of keywords and their type are:

Keyword name	Type	Variable	Default value -------—
ndims	int	HyPar::ndims	1
nvars	int	HyPar::nvars	1
size	int[ndims]	HyPar::dim_global	must be specified
iproc	int[ndims]	MPIVariables::iproc	must be specified
ghost	int	HyPar::ghosts	1
n_iter	int	HyPar::n_iter	0
restart_iter	int	HyPar::restart_iter	0
time_scheme	char[]	HyPar::time_scheme	euler
time_scheme_type	char[]	HyPar::time_scheme_type	none
hyp_space_scheme	char[]	HyPar::spatial_scheme_hyp	1
hyp_flux_split	char[]	HyPar::SplitHyperbolicFlux	no
hyp_interp_type	char[]	HyPar::interp_type	characteristic
par_space_type	char[]	HyPar::spatial_type_par	nonconservative-1stage
par_space_scheme	char[]	HyPar::spatial_scheme_par	2
dt	double	HyPar::dt	0.0
conservation_check	char[]	HyPar::ConservationCheck	no
screen_op_iter	int	HyPar::screen_op_iter	1
file_op_iter	int	HyPar::file_op_iter	1000
op_file_format	char[]	HyPar::op_file_format	text
ip_file_type	char[]	HyPar::ip_file_type	ascii
input_mode	char[]	HyPar::input_mode	serial
output_mode	char[]	HyPar::output_mode	serial
op_overwrite	char[]	HyPar::op_overwrite	no
model	char[]	HyPar::model	must be specified
immersed_body	char[]	HyPar::ib_filename	"none"
size_exact	int[ndims]	HyPar::dim_global_ex	HyPar::dim_global
use_gpu	char[]	HyPar::use_gpu	no
gpu_device_no	int	HyPar::gpu_device_no	-1

Notes:

"ndims" must be specified before "size" and "iproc".
if "input_mode" or "output_mode" are set to "parallel" or "mpi-io", the number of I/O ranks must be specified right after as an integer. For example:
```
begin
    ...
    input_mode  parallel 4
    ...
end
```
This means that 4 MPI ranks will participate in file I/O (assuming total MPI ranks is more than 4) (see ReadArrayParallel(), WriteArrayParallel(), ReadArrayMPI_IO() ).
- The number of I/O ranks specified for "input_mode" and "output_mode" must be same. Otherwise, the value for the one specified last will be used.
- The number of I/O ranks must be such that the total number of MPI ranks is an integer multiple. Otherwise, the code will use only 1 I/O rank.
If any of the keywords are not present, the default value is used, except the ones whose default values say "must be specified". Thus, keywords that are not required for a particular simulation may be left out of the solver.inp input file. For example,
- a Euler1D simulation does not need "par_space_type" or "par_space_scheme" because it does not have a parabolic term.
- unless a conservation check is required, "conservation_check" can be left out and the code will not check for conservation.
- "immersed_body" need not be specified if there are no immersed bodies present. NOTE: However, if it is specified, and a file of that filename does not exist, it will result in an error.

boundary.inp

Requirement: mandatory

Read by: InitializeBoundaries()

Description: Specify boundary conditions.

Format: ASCII text

    nb
    boundary_type   spatial_dimension   face   [extent] 
    boundary_type   spatial_dimension   face   [extent] 
    ...
    boundary_type   spatial_dimension   face   [extent]

where

nb is the number of boundaries
This is followed by at least nb rows, each row specifying:
- boundary_type - Type of boundary, eg. _PERIODIC_, _EXTRAPOLATE_, _DIRICHLET_, etc. See include/boundaryconditions.h for a full list.
- spatial_dimension - The spatial dimension along which this boundary condition applies. Must be in the range 0, 1, ..., HyPar::ndims-1
- face - The face on which this the boundary acts (1 means the left face along the dimension, or the low index end, -1 means the right face along the dimension, or the high index end).
- [extent] - The extent of this boundary (in terms of coordinates, not grid indices). Written as (2 X HyPar::ndims) real numbers: xmin_0 xmax_0 xmin_1 xmax_1 ... ... xmin_(ndims-1) xmax_(ndims-1), where [xmin_i, xmax_i] define the extent along spatial dimension i. Note that the xmin_i and xmax_i for i = spatial_dimension are ignored, but should be there for the sake of a uniform format (they can be set as 0).
For the following boundary types, an additional line is required right below the line specifying that boundary with inputs specific to that boundary type:
- _DIRICHLET_: the next line should specify the boundary value of the solution at that boundary (the value is assumed to be constant in space and time). Each component of the solution must be specified (i.e. HyPar::nvars real numbers).
```
u[0]  u[1]  ... u[#HyPar::nvars-1]
```
- _SLIP_WALL_, _NOSLIP_WALL_, _SW_SLIP_WALL_, or _SW_NOSLIP_WALL_: the next line should specify the wall velocity (assumed to be constant in space and time). Each component of the velocity must be specified (i.e. HyPar::ndims real numbers).
```
u[0]  u[1]  ... u[#HyPar::ndims-1]
```
- _SUBSONIC_INFLOW_: the next line must specify the inflow density and velocity vector (assumed to be constant in space and time). Each component of the velocity must be specified (i.e. HyPar::ndims+1 real numbers)
```
rho  u[0]  u[1]  ... u[#HyPar::ndims-1]
```
- _SUBSONIC_OUTFLOW_: the next line must specify the outflow pressure (assumed to be constant in space and time), i.e., one real number
```
p
```
- _SUPERSONIC_INFLOW_: the next line must specify the inflow density, velocity, and pressure (assumed to be constant in space and time). Each component of the velocity must be specified (i.e. HyPar::ndims+2 real numbers)
```
rho  u[0]  u[1]  ... u[#HyPar::ndims-1]  p
```
  Note that this boundary can also be implemented through the _DIRICHLET_; however, the flow variables must be converted to the conserved variable form to specify the Dirichlet boundary value:
```
rho  rho*u[0]  rho*u[1]  ... rho*u[#HyPar::ndims-1]  E (internal energy)
```
- _TURBULENT_SUPERSONIC_INFLOW_: the next line must specify the inflow mean density, velocity, and pressure (assumed to be constant in space and time), i.e, HyPar::ndims+2 real numbersm and the name of the file that contains the unsteady fluctuation data.
```
rho  u[0]  u[1]  ... u[#HyPar::ndims-1]  p  filename
```

initial.inp

Requirement: mandatory

Read by: InitialSolution(), through ReadArray()

Format: Depends on HyPar::input_mode and HyPar::ip_file_type, specified in solver.inp. See ReadArraySerial(), ReadArrayParallel(), and ReadArrayMPI_IO() to understand the format and data layout of this file.

Description: This file contains the initial solution. It will probably not be created by hand. See the examples provided for codes that generate this file for various problems. The final part in these codes, where the initial solution is written to file, can be reused to generate this file for a new case.

lusolver.inp

Requirement: optional

Read by: tridiagLUInit()

Description: Specify parameters related to LU solvers for tridiagonal systems of equations. This file is relevant only if some method requiring the solution of a tridiagonal system of equations is being used (for example: Interp1PrimFifthOrderCRWENO() ).

Format: ASCII text

    begin
        <keyword>   <value>
        <keyword>   <value>
        <keyword>   <value>
        ...
        <keyword>   <value>
    end

where the list of keywords are:

Keyword name	Type	Variable	Default value -------—
evaluate_norm	int	TridiagLU::evaluate_norm	1
maxiter	int	TridiagLU::maxiter	10
atol	double	TridiagLU::atol	1e-12
rtol	double	TridiagLU::rtol	1e-10
verbose	int	TridiagLU::verbose	0
reducedsolvetype	char[]	TridiagLU::reducedsolvetype	_TRIDIAG_JACOBI_

weno.inp

Requirement: optional

Read by: WENOInitialize()

Description: Specify parameters related to WENO-type spatial discretization. This file is relevant only if a WENO-type method is being used for spatial discretization (for example: Interp1PrimFifthOrderCRWENO(), Interp1PrimFifthOrderWENO(), Interp1PrimFifthOrderHCWENO() ). For most cases, this file is useful if a very specific study on the behavior of the WENO-type method is being carried out; typically, the default values are enough to ensure "good" solutions.

Format: ASCII text

    begin
        <keyword>   <value>
        <keyword>   <value>
        ...
        <keyword>   <value>
    end

where the list of keywords are:

Keyword name	Type	Variable	Default value -------—
mapped	int	WENOParameters::mapped	0
borges	int	WENOParameters::borges	0
yc	int	WENOParameters::yc	0
no_limiting	int	WENOParameters::no_limiting	0
epsilon	double	WENOParameters::eps	1e-6
rc	double	WENOParameters::rc	0.3
xi	double	WENOParameters::xi	0.001
tol	double	WENOParameters::tol	1e-16

physics.inp

Requirement: mandatory/optional (depends on the physical model)

Read by: The initialization function of the various physics modules (eg. Euler1DInitialize(), NavierStokes2DInitialize(), etc)

Description: This file contains inputs specific to a physics model. Depending on the physical model being used, it may or may not be mandatory. The exact parameters to specify depend on the physics.

Format: ASCII text

    begin
        <keyword>   <value>
        <keyword>   <value>
        ...
        <keyword>   <value>
    end

See the documentation for the initialization function of the various phyical models for a list of keywords (for example, Euler1DInitialize(), NavierStokes2DInitialize()).

.petscrc

Requirement: mandatory if using PETSc time integration; if absent, HyPar will use native time integration. If compiled without PETSc, this file is not required.

Read by: PETSc

Description: This file contains the input flags required by PETSc time integration and its associated features.

Format: ASCII text

Note: The contents of this file may also be specified as command line flags.

This file contains all the inputs required for the PETSc time integrators. See PETSc documentation (https://petsc.org/release/docs/) for all the inputs that PETSc needs, or see the PETSc examples for the inputs relevant to HyPar. In addition, following are the HyPar-specific inputs (they are all optional, if not specified, default values are used):

-use-petscts: If this flag is specified, PETSc time integration is used. If not specified, native time integration is used (default).
-jfnk_epsilon <value>: specify \(\epsilon\) parameter for the directional-derivative-based approximation of the Jacobian (relevant only for implicit and IMEX time integration) (default: \(10^{-6}\)).
-with_pc: If this flag is specified, a preconditioning matrix will be assembled for use with the preconditioners available in PETSc. If not specified, no preconditioning will be used (default).

In addition, if an IMEX time integrator (TSARKIMEX - https://petsc.org/release/docs/manualpages/TS/TSARKIMEX.html) is being used, the following terms specify how the hyperbolic, parabolic, and source terms are integrated in time (explicitly or implicitly):

-hyperbolic_explicit: treat hyperbolic term explicitly (default).
-parabolic_explicit: treat parabolic term explicitly.
-source_explicit: treat the source term explicitly.
-hyperbolic_implicit: treat hyperbolic term implicitly.
-parabolic_implicit: treat parabolic term implicitly (default).
-source_implicit: treat the source term implicitly (default).

Immersed Body

Requirement: mandatory if using immersed boundaries (the keyword immersed_body is specified in solver.inp); if absent, HyPar will not use immersed boundaries.

Read by: IBReadBodySTL(), called by the initialization function for immersed boundaries InitializeImmersedBoundaries().

File name: The name of this file must be the same as the value of the keyword immersed_body in solver.inp.

Format: ASCII STL (https://en.wikipedia.org/wiki/STL_%28file_format%29)

Notes:

The normal defined in the STL file must be the "outward" normal, i.e., pointing outside the body.
The geometry must be a closed one.
Some sample STL files are available in hypar/Examples/STLGeometries/

simulation.inp

Requirement: mandatory if running an ensemble/multidomain simulation

Read by: EnsembleSimulation::define()

Description: Specify the parameters related to ensemble simulations.

Format: ASCII text

    begin
        <keyword>   <value>
        <keyword>   <value>
        <keyword>   <value>
        ...
        <keyword>   <value>
    end

where the list of keywords and their type are:

Keyword name	Type	Variable	Default value -------—
nsims	int	EnsembleSimulation::m_nsims	1

Notes:

This file must exist for ensemble simulations; if this file does not exist, HyPar will run a standard single simulation.

sparse_grids.inp

Requirement: mandatory if running with the sparse grids method

Read by: SparseGridsSimulation::define()

Description: Specify the parameters related to sparse grids method.

Format: ASCII text

    begin
        <keyword>   <value>
        <keyword>   <value>
        <keyword>   <value>
        ...
        <keyword>   <value>
    end

where the list of keywords and their type are:

Keyword name	Type	Variable	Default value -------—
log2_imin	int	SparseGridsSimulation::m_imin	2
interp_order	int	SparseGridsSimulation::m_interp_order	6
write_sg_solution	char[]	SparseGridsSimulation::m_write_sg_solutions	no
write_sg_errors	char[]	SparseGridsSimulation::m_print_sg_errors	no

Notes:

Even if you want to use the default values for all the parameters, the file sparse_grids.inp must exist with just the text
```
  begin
  end
```
If this file does not exist, HyPar will not use the sparse grids method.

librom.inp

Requirement: mandatory if one wants to use the libROM (https://www.librom.net/) interface. This file is read only if HyPar is compiled with the libROM interface (see compilation instructions).

Read by: libROMInterface::define(), DMDROMObject::DMDROMObject()

Description: Specify the parameters related to reduced-order modeling using libROM.

Format: ASCII text

    begin
        <keyword>   <value>
        <keyword>   <value>
        <keyword>   <value>
        ...
        <keyword>   <value>
    end

where the list of keywords and their type are:

Keyword name	Type	Variable	Default value -------—
rdim	int	libROMInterface::m_rdim	-1
sampling_frequency	int	libROMInterface::m_sampling_freq	1
mode	string	libROMInterface::m_mode	"train"
component_mode	string	libROMInterface::m_comp_mode	"monolithic"
type	string	libROMInterface::m_rom_type	"DMD"
save_to_file	string	libROMInterface::m_save_ROM	"true"
dmd_num_win_samples	int	DMDROMObject::m_num_window_samples	INT_MAX
dmd_dirname	string	DMDROMObject::m_dirname	"DMD"
dmd_write_snapshot_mat	bool	DMDROMObject::m_write_snapshot_mat	false

Notes:

Even if you want to use the default values for all the parameters, the file librom.inp must exist with just the text
```
  begin
  end
```
If this file does not exist, HyPar will not use the libROM interface.
The default value for rdim is invalid, so it must be specified.