fargo.c File Reference

Solves the linear transport step of the FARGO-MHD algorithm. More...

#include "pluto.h"

Functions
static void	FARGO_Flux (double *, double *, double)
void	FARGO_ShiftSolution (Data_Arr U, Data_Arr Us, Grid *grid)

Detailed Description

Implements a uniform shift of the conservative fluid variables in the direction of orbital motion which is assumed to be (for Cartesian or polar coordinates) or (for spherical coordinates). The shift is converted into an integer part "m" and a fractional remainder "eps".

Parallelization is performed by adding extra data layers above and below the current data set so as to enlarge the required computational stencil in the orbital direction. The additional buffers are received from the processors lying, respectively, below and above and their size changes dynamically from one step to the next.

Reference

• "A conservative orbital advection scheme for simulations of magnetized shear flows with the PLUTO code"
  Mignone et al, A&A (2012) 545, A152 (–> Section 2.4)

Author

A. Mignone (migno.nosp@m.ne@p.nosp@m.h.uni.nosp@m.to.i.nosp@m.t)
G. Muscianisi (g.mus.nosp@m.cian.nosp@m.isi@c.nosp@m.inec.nosp@m.a.it)

Date

Aug 16, 2012

Function Documentation

void FARGO_Flux ( double *  q, double *  flx, double  eps  )

static

Compute the transport flux corresponding to a fractional increment eps.

Parameters

[in]	q	1D array of a conserved quantity
[out]	flx	the conservative flux
[in]	eps	the fractional increment

The following MAPLE script may be used to check the correctness of implementation

restart;
P0 := 3/2*q[i] - (q[p]+q[m])/4;
P1 := q[p] - q[m];
P2 := 3*(q[p] - 2*q[i] + q[m]);

FS[p] := P0 + P1/2*(1 - epsilon) + P2*(1/4 - epsilon/2 + epsilon^2/3);
FS[m] := P0 - P1/2*(1 - epsilon) + P2*(1/4 - epsilon/2 + epsilon^2/3);

dq  := q[p] - q[m];
d2q := q[p] - 2*q[i] + q[m];
FF[p] := q[p] - epsilon/2*(dq + d2q*(3 - 2*epsilon));
FF[m] := q[m] + epsilon/2*(dq - d2q*(3 - 2*epsilon));

void FARGO_ShiftSolution	(	Data_Arr	U,
		Data_Arr	Us,
		Grid *	grid
	)

Shifts conserved variables in the orbital direction.

Parameters

[in,out]	U	a 3D array of conserved, zone-centered values
[in,out]	Us	a 3D array of staggered magnetic fields
[in]	grid	pointer to Grid structure;

Returns

This function has no return value.

Todo:

Optimization: avoid using too many if statement like on nproc_s > 1 or == 1