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Commit 31bacab2 authored by Matthieu Schaller's avatar Matthieu Schaller
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Modified the Gadget-2 interaction to be correct when masses differ.

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2 merge requests!136Master,!90Improved multi-timestep SPH
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src/hydro/Gadget2/hydro_iact.h
+ 30
− 28
View file @ 31bacab2
...@@ -238,18 +238,19 @@ __attribute__((always_inline)) INLINE static void runner_iact_force( ...@@ -238,18 +238,19 @@ __attribute__((always_inline)) INLINE static void runner_iact_force(
const float mu_ij = fac_mu * dvdr * r_inv; const float mu_ij = fac_mu * dvdr * r_inv;
v_sig -= 3.f * mu_ij; v_sig -= 3.f * mu_ij;
const float rho_ij = 0.5f * (rhoi + rhoj); const float rho_ij = 0.5f * (rhoi + rhoj);
const float balsara_i = fabsf(pi->div_v) / (fabsf(pi->div_v) + pi->force.curl_v + const float balsara_i =
0.0001 * ci / fac_mu / hi); fabsf(pi->div_v) /
const float balsara_j = fabsf(pj->div_v) / (fabsf(pj->div_v) + pj->force.curl_v + (fabsf(pi->div_v) + pi->force.curl_v + 0.0001 * ci / fac_mu / hi);
0.0001 * cj / fac_mu / hj); const float balsara_j =
fabsf(pj->div_v) /
(fabsf(pj->div_v) + pj->force.curl_v + 0.0001 * cj / fac_mu / hj);
visc = -0.25f * const_viscosity_alpha * v_sig * mu_ij / rho_ij * visc = -0.25f * const_viscosity_alpha * v_sig * mu_ij / rho_ij *
(balsara_i + balsara_j); (balsara_i + balsara_j);
} }
/* Now, convolve with the kernel */ /* Now, convolve with the kernel */
const float visc_term = 0.5f * mj * visc * (wi_dr + wj_dr) * r_inv; const float visc_term = 0.5f * visc * (wi_dr + wj_dr) * r_inv;
const float sph_term = const float sph_term = (P_over_rho_i * wi_dr + P_over_rho_j * wj_dr) * r_inv;
mj * (P_over_rho_i * wi_dr + P_over_rho_j * wj_dr) * r_inv;
/* Eventually got the acceleration */ /* Eventually got the acceleration */
const float acc = visc_term + sph_term; const float acc = visc_term + sph_term;
...@@ -272,25 +273,25 @@ __attribute__((always_inline)) INLINE static void runner_iact_force( ...@@ -272,25 +273,25 @@ __attribute__((always_inline)) INLINE static void runner_iact_force(
/* message("oO"); */ /* message("oO"); */
/* Use the force Luke ! */ /* Use the force Luke ! */
pi->a_hydro[0] -= acc * dx[0]; pi->a_hydro[0] -= mj * acc * dx[0];
pi->a_hydro[1] -= acc * dx[1]; pi->a_hydro[1] -= mj * acc * dx[1];
pi->a_hydro[2] -= acc * dx[2]; pi->a_hydro[2] -= mj * acc * dx[2];
pj->a_hydro[0] += acc * dx[0]; pj->a_hydro[0] += mi * acc * dx[0];
pj->a_hydro[1] += acc * dx[1]; pj->a_hydro[1] += mi * acc * dx[1];
pj->a_hydro[2] += acc * dx[2]; pj->a_hydro[2] += mi * acc * dx[2];
/* Get the time derivative for h. */ /* Get the time derivative for h. */
pi->h_dt -= mj * dvdr * r_inv / rhoj * wi_dr; pi->h_dt -= mj * dvdr * r_inv / rhoj * wi_dr;
pj->h_dt -= mi * dvdr * r_inv / rhoi * wj_dr; pj->h_dt -= mi * dvdr * r_inv / rhoi * wj_dr;
/* Update the signal velocity. */ /* Update the signal velocity. */
pi->force.v_sig = fmaxf(pi->force.v_sig, v_sig); pi->force.v_sig = fmaxf(pi->force.v_sig, v_sig);
pj->force.v_sig = fmaxf(pj->force.v_sig, v_sig); pj->force.v_sig = fmaxf(pj->force.v_sig, v_sig);
/* Change in entropy */ /* Change in entropy */
pi->entropy_dt += 0.5f * visc_term * dvdr; pi->entropy_dt += 0.5f * mj * visc_term * dvdr;
pj->entropy_dt -= 0.5f * visc_term * dvdr; pj->entropy_dt -= 0.5f * mi * visc_term * dvdr;
} }
/** /**
...@@ -349,35 +350,36 @@ __attribute__((always_inline)) INLINE static void runner_iact_nonsym_force( ...@@ -349,35 +350,36 @@ __attribute__((always_inline)) INLINE static void runner_iact_nonsym_force(
const float mu_ij = fac_mu * dvdr * r_inv; const float mu_ij = fac_mu * dvdr * r_inv;
v_sig -= 3.f * mu_ij; v_sig -= 3.f * mu_ij;
const float rho_ij = 0.5f * (rhoi + rhoj); const float rho_ij = 0.5f * (rhoi + rhoj);
const float balsara_i = fabsf(pi->div_v) / (fabsf(pi->div_v) + pi->force.curl_v + const float balsara_i =
0.0001 * ci / fac_mu / hi); fabsf(pi->div_v) /
const float balsara_j = fabsf(pj->div_v) / (fabsf(pj->div_v) + pj->force.curl_v + (fabsf(pi->div_v) + pi->force.curl_v + 0.0001 * ci / fac_mu / hi);
0.0001 * cj / fac_mu / hj); const float balsara_j =
fabsf(pj->div_v) /
(fabsf(pj->div_v) + pj->force.curl_v + 0.0001 * cj / fac_mu / hj);
visc = -0.25f * const_viscosity_alpha * v_sig * mu_ij / rho_ij * visc = -0.25f * const_viscosity_alpha * v_sig * mu_ij / rho_ij *
(balsara_i + balsara_j); (balsara_i + balsara_j);
} }
/* Now, convolve with the kernel */ /* Now, convolve with the kernel */
const float visc_term = 0.5f * mj * visc * (wi_dr + wj_dr) * r_inv; const float visc_term = 0.5f * visc * (wi_dr + wj_dr) * r_inv;
const float sph_term = const float sph_term = (P_over_rho_i * wi_dr + P_over_rho_j * wj_dr) * r_inv;
mj * (P_over_rho_i * wi_dr + P_over_rho_j * wj_dr) * r_inv;
/* Eventually got the acceleration */ /* Eventually got the acceleration */
const float acc = visc_term + sph_term; const float acc = visc_term + sph_term;
/* Use the force Luke ! */ /* Use the force Luke ! */
pi->a_hydro[0] -= acc * dx[0]; pi->a_hydro[0] -= mj * acc * dx[0];
pi->a_hydro[1] -= acc * dx[1]; pi->a_hydro[1] -= mj * acc * dx[1];
pi->a_hydro[2] -= acc * dx[2]; pi->a_hydro[2] -= mj * acc * dx[2];
/* Get the time derivative for h. */ /* Get the time derivative for h. */
pi->h_dt -= mj * dvdr * r_inv / rhoj * wi_dr; pi->h_dt -= mj * dvdr * r_inv / rhoj * wi_dr;
/* Update the signal velocity. */ /* Update the signal velocity. */
pi->force.v_sig = fmaxf(pi->force.v_sig, v_sig); pi->force.v_sig = fmaxf(pi->force.v_sig, v_sig);
/* Change in entropy */ /* Change in entropy */
pi->entropy_dt += 0.5f * visc_term * dvdr; pi->entropy_dt += 0.5f * mj * visc_term * dvdr;
} }
#endif /* SWIFT_RUNNER_IACT_LEGACY_H */ #endif /* SWIFT_RUNNER_IACT_LEGACY_H */
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