Immersed-boundary Block¶

The Immersed-boundary Block defines how complex, arbitrarily shaped solid boundaries are embedded into the computational domain without the need for body-fitted meshing. It provides mechanisms for prescribing solid geometry, enforcing no-slip and impermeability conditions, and applying forcing terms that reconstruct the correct boundary behavior within a Cartesian or structured mesh. This block offers flexible tools for simulating moving bodies, various thermal boundary conditions, and geometries with deformations, while preserving the simplicity and efficiency of regular-grid discretizations.

Warning

This block is optional.

Flags Overview¶

Note

All flags and their description are included in the table below. A detailed description of which values are possible for each input flag follows.

Flag	Required	Description
`IB_GEOMETRY`	No	determine whether to activate the direct-boundary immersed boundary method.
`IB_GHOST`	No	determine whether to activate the directional ghost-cell immersed boundary method.
`IB_NUMBER`	No	specify the number of immersed bodies in the domain.
`IB_RADIUS`	No	real values, specify the radius of the spherical body.
`IB_RADIUS`	No	real values, specify the radius of the spherical body.
`READ_SDF`	No	determine how the level-set function is obtained for the immersed geometry.
`IB_XVEL`	No	real values, pre-defined velocity component in $x$ direction for moving geometries.
`IB_YVEL`	No	real values, pre-defined velocity component in $y$ direction for moving geometries.
`IB_ZVEL`	No	real values, pre-defined velocity component in $z$ direction for moving geometries.
`IB_WVEL`	No	real values, pre-defined rotating velocity for moving geometries.
`IB_DATA`	No	string variable, defines the name of a binary data file describing a specific geometry when READ_SDF=.true..
`IB_DATA_TYPE`	No	integer values, geometry data type, 0 for Eulerian data (coinciding with the grid location), 1 for Lagrangian data (not coinciding with the grid location).
`PROJECTION_POINTS`	No	positive integer number from 1 to 4, determines the interpolation order from Lagrangian points to the Eulerian ones.
`IB_FLOW`	No	string variable, determines whether the flow is internal ('internal_flow') or external ('external_flow').
`PIS_VEL`	No	Moving piston velocity, specified for motion along the $x$ direction.
`IC_COMPRESS`	No	determine whether to simulate the internal combustion engine with moving piston; the default is .false..
`IC_REACTION`	No	determine whether to simulate the reaction flow in the internal combustion engine; the default is .false..
`DINO_TIME_REACTION`	No	the current physical time used for evaluating time-dependent immersed-boundary motion.
`ISOTHERMAL_IBM`	No	determine whether to activate the iso-thermal boundary condition.
`ADIABATIC_IBM`	No	determine whether to activate the adiabatic boundary condition.
`CHT_IBM`	No	determine whether to activate the conjugate heat transfer boundary condition.
`SOLID_RHO`	No	real values, specify the density of the solid material when CHT_IBM=.true..
`SOLID_CONDUC`	No	real values, specify the thermal conductivity of the solid material when CHT_IBM=.true..
`SOLID_CP`	No	real values, specify the specific heat capacity of the solid material when CHT_IBM=.true..
`HEAT_SOURCE`	No	real values, specify the heat source term within the solid when CHT_IBM=.true..

Flags Details¶

IB_GEOMETRY

Type: boolean
Default: .false.
Description: To use Direct boundary IBM, you should generate your own geometry data file. The employed DB-IBM can only deliver 0th-order accuracy. Therefore, with DB-IBM, be prepared to use enough grid points. Note: this method is not recommended any more in the current version of DINO.

IB_GHOST

Type: boolean
Default: .true.
Description: An advanced ghost-cell immersed-boundary formulation that reconstructs boundary conditions using directional interpolation aligned with the discretization directions. This method provides a sharp and accurate representation of complex geometries, significantly reducing numerical diffusion near solid surfaces and offering improved stability over traditional direct-forcing approaches. Note: this is the recommended immersed-boundary method in the current version of the code.

IB_NUMBER

Type: integer
Default: 1
Description: Currently, only spherical bodies are supported. For other geometrically regular bodies that can be described analytically, the corresponding treatment can be modified in the relevant sections of dino_ib_mod_no_surface_reaction.f90 and/or dino_ib_mod_surface_reaction.f90

IB_RADIUS

Type: REAL
Default: 25E-6
Description: It determines the radius of each sphere of the immersed boundary, the corresponding treatment can be modified in the relevant sections of dino_ib_mod_no_surface_reaction.f90 and/or dino_ib_mod_surface_reaction.f90
Description: Currently, only spherical bodies are supported. For other geometrically regular bodies that can be described analytically, the corresponding treatment can be modified in the relevant sections of dino_ib_mod_no_surface_reaction.f90 and/or dino_ib_mod_surface_reaction.f90

IB_RADIUS

Type: REAL
Default: 25E-6
Description: It determines the radius of each sphere of the immersed boundary, the corresponding treatment can be modified in the relevant sections of dino_ib_mod_no_surface_reaction.f90 and/or dino_ib_mod_surface_reaction.f90

READ_SDF

Type: boolean
Default: .false.
Description: Specify how the level-set function, typically a signed distance representation of the geometry, is obtained, either from an analytical expression (READ_SDF=.false.) or reconstructed from an STL surface mesh (READ_SDF=.true.) . If READ_SDF=.false., the level-set function is generated internally in dino_ib_mod_no_surface_reaction.f90 using the corresponding explicit function to describe the signed distance from each grid point to the boundary. If READ_SDF = .true., the level-set values are loaded from a binary file generated using the tools SDFGen and write_io_parallel located in $dino_home/TOOLS/SDF.

IB_XVEL

Type: REAL
Default: 0
Description: It determines the pre-defined velocity component in $x$ in case of moving IBM, the corresponding treatment can be modified in the relevant sections of dino_ib_mod_no_surface_reaction.f90 and/or dino_ib_mod_surface_reaction.f90

IB_YVEL

Type: REAL
Default: 0
Description: It determines the pre-defined velocity component in $y$ in case of moving IBM, the corresponding treatment can be modified in the relevant sections of dino_ib_mod_no_surface_reaction.f90 and/or dino_ib_mod_surface_reaction.f90

IB_ZVEL

Type: REAL
Default: 0
Description: It determines the pre-defined velocity component in $z$ in case of moving IBM, the corresponding treatment can be modified in the relevant sections of dino_ib_mod_no_surface_reaction.f90 and/or dino_ib_mod_surface_reaction.f90

IB_WVEL

Type: REAL
Default: 0
Description: It determines a pre-defined rotating velocity for moving geometries, the corresponding treatment can be modified in the relevant sections of dino_ib_mod_no_surface_reaction.f90 and/or dino_ib_mod_surface_reaction.f90

IB_DATA

Type: String
Default: 'file_name_ibm.sdf'
Description: It defines the name of a binary data file describing a specific geometry when READ_SDF=.true.., the corresponding treatment can be modified in the relevant sections of dino_ib_mod_no_surface_reaction.f90 and/or dino_ib_mod_surface_reaction.f90

IB_DATA_TYPE

Type: integer
Default: 0
Description: Integer values define the geometry data type, 0 for Eulerian data (coinciding with the grid location), 1 for Lagrangian data (not coinciding with the grid location), the corresponding treatment can be modified in the relevant sections of dino_ib_mod_no_surface_reaction.f90 and/or dino_ib_mod_surface_reaction.f90

PROJECTION_POINTS

Type: Integer
Default: 1
Description: It is a positive integer number from 1 to 4, determines the interpolation order from Lagrangian points to the Eulerian ones, the corresponding treatment can be modified in the relevant sections of dino_ib_mod_no_surface_reaction.f90 and/or dino_ib_mod_surface_reaction.f90

IB_FLOW

Type: String
Default: 'external_flow'
Description: It determines whether the flow is internal ('internal_flow') or external ('external_flow').

PIS_VEL

Type: REAL
Default: 0
Description: Sets the piston velocity in x-direction in an internal combustion engine simulation.

IC_COMPRESS

Type: boolean
Default: .false.
Description: Activates the computation of a compression stroke of an internal combustion engine.

IC_REACTION

Type: boolean
Default: .false.
Description: Activates the reactive flow simulation for an internal combustion engine simulation.

DINO_TIME_REACTION

Type: REAL
Default: 0
Description: The current physical time used for evaluating time-dependent immersed-boundary motion.

ISOTHERMAL_IBM

Type: boolean
Default: .true.
Description: It determines whether to activate the iso-thermal boundary condition.

ADIABATIC_IBM

Type: boolean
Default: .false.
Description: It determines whether to activate the adiabatic boundary condition (wall normal gradient is zero).

CHT_IBM

Type: boolean
Default: .false.
Description: It determines whether to activate the conjugate heat transfer boundary condition. For multilayer solid-fluid interface, the corresponding treatment can be modified in the subroutine CHT_ghost_solid of dino_ib_ghost_cht.f90.

SOLID_RHO

Type: REAL
Default: 2700.
Description: It specifies the density of the solid material when CHT_IBM=.true..

SOLID_CONDUC

Type: REAL
Default: 237.0
Description: It specifies the thermal conductivity of the solid material when CHT_IBM=.true..

SOLID_CP

Type: REAL
Default: 897.0
Description: It specifies the specific heat capacity of the solid material when CHT_IBM=.true..

HEAT_SOURCE

Type: REAL
Default: 0.0
Description: It specifies the heat source term within the solid when CHT_IBM=.true..

Example:¶

&NML_IMMERSED_BOUNDARY
    IB_GEOMETRY=.false.
    IB_GHOST=.FALSE.
    IB_NUMBER = 1,
    IB_RADIUS = 1.e-3,
    READ_SDF=.true.
    IB_XVEL = 0.d0,
    IB_YVEL = 0.d0,
    IB_ZVEL = 0.d0,
    IB_WVEL = 0.d0,
    IB_DATA='bb_wo_coflow_2dslab_3DX_6DZ_binary.sdf',
    IB_DATA_TYPE=0, 
    PROJECTION_POINTS=1,
    IB_FLOW='external_flow',
    PIS_VEL = 41800,
    IC_COMPRESS = .false.
    IC_REACTION = .false.
    DINO_TIME_REACTION = 0.D0,
    ISOTHERMAL_IBM = .true.
    ADIABATIC_IBM = .false.
    CHT_IBM = .false.
    SOLID_RHO = 2700.
    SOLID_CONDUC=237.0, 
    SOLID_CP=897.0,
    HEAT_SOURCE=0.0,
/