# dissipation2D Section

This section configures **2D dissipation parameters**, including **bottom friction**, **horizontal viscosity**, and **Smagorinsky coefficients**.

---

 | **Parameter** | **Description** |
 |---------------|----------------|
 | `background_velocity_mode` | Mode for background velocity (`UNDEFINED`, `UNIFORM`, `POLYGONS`, `RASTER`, `NODEFILE`). |
 | `min_background_speed` | Minimum background speed (default: `0.05 m/s`). |
 | `BKG_polygones` | File for background velocity polygons. |
 | `BKG_values` | File for background velocity values. |
 | `background_velocity_file` | File for background velocity. |
 | `bottom_friction_type` | Type of bottom friction (`LINEAR`, `QUADRATIC_CD`, `QUADRATIC_Z0`, `QUADRATIC_MANNING`). |
 | `linear_friction_coeff` | Linear bottom friction coefficient (default: `2.5e-3`, dimensionless). |
 | `quadratic_friction_coeff` | Quadratic bottom friction coefficient (default: `2.5e-3`, dimensionless). |
 | `QFC_polygones` | File for quadratic friction coefficient polygons. |
 | `QFC_values` | File for quadratic friction coefficient values. |
 | `bottom_coeff_file` | File for prescribed bottom friction coefficient (LGP1 discretization). |
 | `roughness_length` | Equivalent roughness length for quadratic bottom friction (default: `1.0e-4 m`). |
 | `min_quadratic_friction_coeff` | Minimum value for Cd when using roughness formulation (default: `-999`, dimensionless). |
 | `QFCM_polygones` | File for minimum quadratic friction coefficient polygons. |
 | `QFCM_values` | File for minimum quadratic friction coefficient values. |
 | `bottom_rugosity_file` | File for prescribed roughness length (LGP1 discretization). |
 | `rugosity_polygones` | File for rugosity polygons. |
 | `rugosity_values` | File for rugosity values. |
 | `rugosity_values_by_regions` | File for rugosity values by regions. |
 | `manning_coefficient` | Manning coefficient (default: `1.e-02`, dimensionless). |
 | `manning_coefficient_file` | File for prescribed Manning coefficient (LGP1 discretization). |
 | `localized_parameters_echoing` | Flag to echo localized parameters (`TRUE`, `FALSE`). |
 | `viscous_friction_coeff` | Viscous bottom friction coefficient (default: `1.18e-4`, dimensionless). |
 | `internal_drag_algorithm` | Algorithm for internal drag (`0`, `1`, `2`, `3`, `4`, `5`). |
 | `internal_drag_slope` | Slope for internal drag (default: `0.00`, dimensionless). |
 | `internal_drag_hmin` | Minimum depth for internal drag (default: `300`, dimensionless). |
 | `internal_drag_hmax` | Maximum depth for internal drag (default: `500`, dimensionless). |
 | `internal_drag_polygones` | File for internal drag polygons. |
 | `internal_drag_values` | File for internal drag values. |
 | `internal_drag_values_by_regions` | File for internal drag values by regions. |
 | `internal_drag_rugosity` | Rugosity for internal drag (default: `0.00`, dimensionless). |
 | `mixed_layer_coeff` | Mixed layer coefficient (default: `0.00 m/s`). |
 | `horizontal_viscosity_mode` | Mode for horizontal viscosity (`NONE`, `SMAGORINSKY`, `PROPORTIONAL`, `CONSTANT`, `SMAGORINSKY-2D`). |
 | `min_horizontal_viscosity` | Minimum horizontal viscosity (default: `1.00 m²/s`). |
 | `max_horizontal_viscosity` | Maximum horizontal viscosity (default: `1000.00 m²/s`). |
 | `smagorinsky_coefficient` | Smagorinsky coefficient (default: `0.28`, dimensionless). |
 | `smagorinski_coefficient_polygons` | File for Smagorinsky coefficient polygons. |
 | `smagorinski_coefficient_values` | File for Smagorinsky coefficient values. |
 | `lateral_friction_type` | Type of lateral friction (`LINEAR`, `QUADRATIC_CD`). |
 | `lateral_friction_linear_coeff` | Linear lateral friction coefficient (default: `1.0e-3`, dimensionless). |
 | `shear_drag_flag` | Flag to enable/disable dissipation in mixing layer (`TRUE`, `FALSE`). |
 | `brunt_vassalla_value` | Brunt-Väisälä value (default: `0.002 s`). |
 | `brunt_vassalla_file` | File for local Brunt-Väisälä values. |