Poisson Solver Block¶

The Poisson Solver Block handles the solution of Poisson-type equations that arise in the simulation, typically used for pressure correction, potential fields, or enforcing divergence constraints. In DINO, the Possion equation is solved by FFT, even when the boundary conditions of the domain are not periodic.

Warning

This block is mandatory for all simulations.

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
`PRESSURE_SPECTRAL_SOLVER`	Yes	poisson solver for (fluctuating) pressure.
`INCOMPRESSIBLE`	Yes	.true. when using the fully incompressible solver, and .false. when using the low-Mach solver.
`DPDT_HYD_ON`	No	.true. when considering \(\partial p / \partial t\) in the temperature equation; defalut is .false..
`PGRADX`	No	a constant pressure gradient added into \(x\) direction.
`PGRADY`	No	a constant pressure gradient added into \(y\) direction.
`PGRADZ`	No	a constant pressure gradient added into \(z\) direction.
`SUPPRESS_NOISE_X`	No	Noise suppression from the fluctuating pressure in \(x\) direction.
`SUPPRESS_NOISE_Y`	No	Noise suppression from the fluctuating pressure in \(y\) direction.
`SUPPRESS_NOISE_Z`	No	Noise suppression from the fluctuating pressure in \(z\) direction.
`REMOVE_MEAN_PRESSURE`	No	remove mean value of pressure fluctuations.

Flags Details¶

PRESSURE_SPECTRAL_SOLVER

Type: boolean
Default: .true.
Description: solves the pressure term using a fully spectral method when set to .true.; when set to .false., the solver switches to the HYPRE library.

PGRAD

Type: boolean
Default: .FALSE.
Description: if one of them is set to .true., a constant pressure gradient will be added into the corresponding direction. These work only with Poiseuille flow.

SUPPRESS_NOISE

Type: boolean
Default: .FALSE.
Description: if one of them is set to .true., to suppress noise if source term (pressure) is in fact constant along the corresponding direction. It is optional, the computation can survive without it.

REMOVE_MEAN_PRESSURE

Type: boolean
Default: .FALSE.
Description: remove the mean pressure in case of periodic boundary conditions.

Example:¶

&NML_POISSON_SOLVER
    PRESSURE_SPECTRAL_SOLVER=.true.,
    INCOMPRESSIBLE=.false.,
    DPDT_HYD_ON=.FALSE.,
    PGRADX=.false.,  
    PGRADY=.false., 
    PGRADZ=.false.,
    SUPPRESS_NOISE_X=.FALSE.,
    SUPPRESS_NOISE_Y=.FALSE.,
    SUPPRESS_NOISE_Z=.FALSE.,
    REMOVE_MEAN_PRESSURE=.FALSE.
/