{
  "length_mm": 20,
  "probe_radius_mm": 2,
  "chamber_radii_mm": [
    2.5,
    3,
    4
  ],
  "flow_mm3_s": 5,
  "viscosity_Pa_s": 0.01,
  "density_kg_m3": 1000,
  "diffusivity_mm2_s": 0.0005,
  "probe_region": {
    "z_min_mm": 8,
    "z_max_mm": 12,
    "radial_depth_mm": 0.2
  },
  "pressure_budget_Pa": 10,
  "minimum_radial_clearance_mm": 0.5,
  "tracer_threshold": 0.01,
  "meshes": [
    [
      40,
      12
    ],
    [
      80,
      24
    ],
    [
      160,
      48
    ]
  ],
  "time_steps_s": [
    0.25,
    0.125
  ],
  "maximum_reynolds_number": 0.1,
  "notes": "Reference Newtonian liquid and passive tracer. Uniform annular chamber with a full-length cylindrical probe. No expansion cavities, side ports, adsorption, bubbles or sensor kinetics."
}