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bug in vmvisc #24

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Merged
larsblatny merged 1 commit into from
Mar 6, 2026
Merged

bug in vmvisc #24

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32 changes: 18 additions & 14 deletions src/simulation/plasticity.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -207,14 +207,16 @@ void Simulation::plasticity(unsigned int p, unsigned int & plastic_count, TM & F
delta_gamma = (q_trial-q_yield) / (f_mu_prefac + q_yield*visc_time/dt);
}
if (delta_gamma < 0){
debug("DPVisc: FATAL negative delta_gamma = ", delta_gamma);
debug("VMVisc: FATAL negative delta_gamma = ", delta_gamma);
exit = 1;
}
}
else{

delta_gamma = 0.01 * (q_trial - q_yield) / f_mu_prefac; // initial guess
int max_iter = 60;
T residual;
T residual_diff;
for (int iter = 0; iter < max_iter; iter++) {
if (iter == max_iter - 1){ // did not break loop
debug("VMVisc: FATAL did not exit loop at iter = ", iter);
Expand All @@ -224,8 +226,7 @@ void Simulation::plasticity(unsigned int p, unsigned int & plastic_count, TM & F
q_yield = q_min + (q_max - q_min) * exp(-xi * (particles.eps_pl_dev[p] + (1.0/d_prefac) * delta_gamma));
T q_yield_diff = -xi / d_prefac * (q_max - q_min) * exp(-xi * (particles.eps_pl_dev[p] + (1.0/d_prefac) * delta_gamma));

T residual;
T residual_diff;

if (use_duvaut_lions_formulation){

residual = q_trial - q_yield - f_mu_prefac * ( std::pow(visc_time/dt*delta_gamma, visc_exponent) + delta_gamma );
Expand All @@ -241,17 +242,18 @@ void Simulation::plasticity(unsigned int p, unsigned int & plastic_count, TM & F
T tmp = dt / tm;
T tmp1 = std::pow(tmp, visc_exponent);

T residual = (q_trial - f_mu_prefac * delta_gamma) * tmp1 - q_yield;
residual = (q_trial - f_mu_prefac * delta_gamma) * tmp1 - q_yield;
if (std::abs(residual) < 1e-2) {
break;
}

T residual_diff = -f_mu_prefac * tmp1 + (q_trial - f_mu_prefac * delta_gamma) * visc_exponent * std::pow(tmp, visc_exponent - 1) * (-visc_time * dt) / (tm * tm) - q_yield_diff;
residual_diff = -f_mu_prefac * tmp1 + (q_trial - f_mu_prefac * delta_gamma) * visc_exponent * std::pow(tmp, visc_exponent - 1) * (-visc_time * dt) / (tm * tm) - q_yield_diff;
}

if (std::abs(residual_diff) < 1e-14){ // otherwise division by zero
debug("VMVisc: residual_diff too small in abs value = ", residual_diff);
exit = 1;
T diff_tol = 1e-14;
if (std::abs(residual_diff) < diff_tol){ // otherwise division by zero
debug("VMVisc: WARNING residual_diff too small in abs value = ", residual_diff);
residual_diff = (residual_diff >= 0 ? diff_tol : -diff_tol);
}

delta_gamma -= residual / residual_diff;
Expand Down Expand Up @@ -362,9 +364,10 @@ void Simulation::plasticity(unsigned int p, unsigned int & plastic_count, TM & F

}

if (std::abs(residual_diff) < 1e-14){ // otherwise division by zero
debug("DPVisc: FATAL residual_diff too small in abs value = ", residual_diff);
exit = 1;
T diff_tol = 1e-14;
if (std::abs(residual_diff) < diff_tol){ // otherwise division by zero
debug("DPVisc: WARNING residual_diff too small in abs value = ", residual_diff);
residual_diff = (residual_diff >= 0 ? diff_tol : -diff_tol);
}

delta_gamma -= residual / residual_diff;
Expand Down Expand Up @@ -628,9 +631,10 @@ void Simulation::plasticity(unsigned int p, unsigned int & plastic_count, TM & F

T residual_diff = -f_mu_prefac * tmp1 + (q_trial - f_mu_prefac * delta_gamma) * visc_exponent * std::pow(tmp, visc_exponent - 1) * (-visc_time * dt) / (tm * tm);

if (std::abs(residual_diff) < 1e-14){ // otherwise division by zero
debug("MCCVisc: FATAL residual_diff too small in abs value = ", residual_diff);
exit = 1;
T diff_tol = 1e-14;
if (std::abs(residual_diff) < diff_tol){ // otherwise division by zero
debug("MCCVisc: WARNING residual_diff too small in abs value = ", residual_diff);
residual_diff = (residual_diff >= 0 ? diff_tol : -diff_tol);
}

delta_gamma -= residual / residual_diff;
Expand Down