const.h

/*******************************************************************************
 * This file is part of SWIFT.
 * Copyright (c) 2012 Pedro Gonnet (ptcedro.gonnet@durham.ac.uk)
 *                    Matthieu Schaller (matthieu.schaller@durham.ac.uk)
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 ******************************************************************************/
#ifndef SWIFT_CONST_H
#define SWIFT_CONST_H

/* Hydrodynamical constants. */
#define const_hydro_gamma (5.0f / 3.0f)

/* SPH Viscosity constants. */
#define const_viscosity_alpha \
  0.8f /* Used in the legacy gadget-2 SPH mode only */
#define const_viscosity_alpha_min \
  0.1f /* Values taken from (Price,2004), not used in legacy gadget mode */
#define const_viscosity_alpha_max \
  2.0f /* Values taken from (Price,2004), not used in legacy gadget mode */
#define const_viscosity_length \
  0.1f /* Values taken from (Price,2004), not used in legacy gadget mode */

/* SPH Thermal conductivity constants. */
#define const_conductivity_alpha \
  1.f /* Value taken from (Price,2008), not used in legacy gadget mode */

/* Time integration constants. */
#define const_cfl 0.1f
#define const_ln_max_h_change                                           \
  0.231111721f /* Particle can't change volume by more than a factor of \
                  2=1.26^3 over one time step */
#define const_max_u_change 0.1f

/* Neighbour search constants. */
#define const_eta_kernel \
  1.2349f /* Corresponds to 48 ngbs with the cubic spline kernel */
#define const_delta_nwneigh 0.1f
#define const_smoothing_max_iter 30
#define CUBIC_SPLINE_KERNEL

/* Gravity stuff. */
#define const_theta_max                                   \
  0.57735f /* Opening criteria, which is the ratio of the \
              cell distance over the cell width. */

#define const_G 6.672e-8f             /* Gravitational constant. */
#define const_epsilon 0.0014f         /* Gravity blending distance. */
#define const_iepsilon 714.285714286f /* Inverse gravity blending distance. */
#define const_iepsilon2 (const_iepsilon* const_iepsilon)
#define const_iepsilon3 (const_iepsilon2* const_iepsilon)
#define const_iepsilon4 (const_iepsilon2* const_iepsilon2)
#define const_iepsilon5 (const_iepsilon3* const_iepsilon2)
#define const_iepsilon6 (const_iepsilon3* const_iepsilon3)

/* SPH variant to use */
//#define MINIMAL_SPH
#define GADGET2_SPH
//#define DEFAULT_SPH

/* System of units */
#define const_unit_length_in_cgs 1   /* 3.08567810e16  /\* 1Mpc *\/ */
#define const_unit_mass_in_cgs 1     /* 1.9891e33      /\* 1 M_sun *\/ */
#define const_unit_velocity_in_cgs 1 /* 1e5            /\* km s^-1 *\/ */

#endif /* SWIFT_CONST_H */