{
  "fluid": {"density_kg_m3":1000,"nominal_viscosity_Pa_s":0.75,"viscosities_Pa_s":[0.5,0.75,1.0],"model":"isothermal incompressible Newtonian liquid; reference properties, not a measured product"},
  "nominal_flow_mm3_s":20,
  "flow_rates_mm3_s":[10,20,30],
  "pressure_budget_Pa":6500,
  "retained_volume_limit_mm3":60,
  "body_radius_mm":3,
  "candidates":[
    {"id":"baseline","z_mm":[0,6,14,20],"r_mm":[1,1,0.5,0.5]},
    {"id":"long-taper","z_mm":[0,4,18,20],"r_mm":[1,1,0.5,0.5]},
    {"id":"wide-inlet","z_mm":[0,4,18,20],"r_mm":[1.25,1.25,0.5,0.5]}
  ],
  "meshes":[[40,8],[80,16],[120,24]],
  "maximum_reynolds_number":0.1
}