cngf-pf

commit 169a3e9cb29a2010a6d25dba71998e869bf7a446
parent 77c07cecbee823a1a38ccebab52a55d69f3c4d1e
Author: Anders Damsgaard <anders@adamsgaard.dk>
Date:   Wed, 14 Jan 2026 09:50:22 +0100

fix(simulation): improve velocity residual normalization stability

Use reference velocity scale based on max of absolute values to prevent error amplification when dividing by small velocities.

Diffstat:
M
simulation.c
 | 
4
++--

1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/simulation.c b/simulation.c
@@ -885,8 +885,8 @@ coupled_shear_solver(struct simulation *sim,
 		} while (sim->transient);
 		if (!isnan(sim->v_x_limit) || !isnan(sim->v_x_fix)) {
 			if (!isnan(sim->v_x_limit)) {
-				vel_res_norm = (sim->v_x_limit - sim->v_x[sim->nz - 1])
-				               / (sim->v_x[sim->nz - 1] + 1e-12);
+				double v_ref = fmax(fabs(sim->v_x_limit), fabs(sim->v_x[sim->nz - 1])) + 1e-12;
+				vel_res_norm = (sim->v_x_limit - sim->v_x[sim->nz - 1]) / v_ref;
 				if (vel_res_norm > 0.0)
 					vel_res_norm = 0.0;
 			} else {