PLUTO Test Problems
4.4-patch2
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Rayleigh-Taylor instability setup for hydro or MHD. More...
Functions | |
void | InitDomain (Data *d, Grid *grid) |
Sets the initial condition for a Rayleigh-Taylor instability problem in 2 or 3 dimensions. The initial condition consists of an interface separating two fluids with different densities in hydrostatic balance:
where is the density of the fluid on top,
g
is the (constant) gravity pointing in the negative y
direction. The value of the pressure at the interface (p0
) is chosen in such a way that the sound speed in the light fluid is 1. Likewise, density is normalized to the value in the light fluid. The horizontal extent of the computational domain defines the unit length: Lx=1
.
For magnetized setups, the magnetic field is purely horizontal:
where Bc
is the critical magnetic field above which perturbations parallel to the magnetic field are suppressed (see Boyd & Sanderson, page 99) while the value of is user-supplied (note that a factor
needs to be incorporated when initializing
B
in code units).
The system is destabilized by perturbing the vertical velocity in proximity of the interface using a single mode (in 2D) or a Gaussian perturbation (in 3D). Aleternatively, a random perturbation can be used by setting USE_RANDOM_PERTURBATION
to YES
in your definitions.h
. The runtime parameters that are read from pluto.ini
are
g_inputParam[ETA]
: sets the density of the upper fluid;g_inputParam[GRAV]
: sets gravity (must be < 0);g_inputParam[CHI]
: sets the magnetic field strength in unit of the critical magnetic field Bc
;p0
by a factor q^2
is equivalent to increase gravity of the same factor and decrease velocity and time by a factor q
.The Rayleigh-Taylor setup has been tested with the following configurations:
Conf. | PHYSICS | GEOMETRY | DIM | T. STEP. | INTERP. | divB | Notes |
---|---|---|---|---|---|---|---|
#01 | HD | CARTESIAN | 2 | HANCOCK | LINEAR | - | - |
#02 | HD | CARTESIAN | 2 | RK3 | MP5_FD | - | - |
#03 | HD | CARTESIAN | 2 | RK3 | PARABOLIC | - | - |
#04 | HD | CARTESIAN | 2 | RK2 | LINEAR | - | (*) |
#05 | MHD | CARTESIAN | 2 | HANCOCK | LINEAR | CT | - |
#06 | MHD | CARTESIAN | 2 | RK3 | MP5_FD | GLM | - |
#07 | MHD | CARTESIAN | 2 | RK3 | PARABOLIC | CT | - |
#08 | MHD | CARTESIAN | 2 | ChTr | PARABOLIC | GLM | (*) |
#09 | MHD | CARTESIAN | 3 | RK2 | LINEAR | GLM | - |
#10 | MHD | CARTESIAN | 3 | HANCOCK | LINEAR | GLM | [Mig12](*) |
(*) Setups for AMR-Chombo
References: