Datasets:

yirens
/

double-delta-aero

Each JSON file contains VLM simulation data for a specific geometry configuration. The files are named using a geometry callsign pattern (e.g., 020101-4TM.json).

Top-Level Structure

Each JSON file has two main top-level keys:

{
  "vlm_vd": { ... },  // VLM vortex distribution/geometry data
  "runs": [ ... ]     // Array of simulation runs
}

1. `vlm_vd` (VLM Vortex Distribution)

The vlm_vd object contains geometry and mesh information for the VLM simulation. It includes the following keys:

Coordinate Arrays (960 elements each)

These arrays define the 3D coordinates of various points in the vortex lattice mesh: See SUAVE.Methods.Aerodynamics.Common.Fidelity_Zero.Lift.generate_vortex_distribution.py for VD definition.

XA1 ____________________________ XB1    
   |                            |
   |        bound vortex        |
XAH|  ________________________  |XBH
   | |           XCH          | |
   | |                        | |
   | |                        | |     
   | |                        | |
   | |                        | |
   | |           0 <--control | |       
   | |          XC     point  | |  
   | |                        | |

XA2 ||______________________||XB2 | |
| trailing |
| <-- vortex --> |
| legs |

XCH, YCH, ZCH: Quarter chord vortex bonds coordinates
XA1, YA1, ZA1: Leading edge point A1 coordinates
XA2, YA2, ZA2: Leading edge point A2 coordinates
XB1, YB1, ZB1: Trailing edge point B1 coordinates
XB2, YB2, ZB2: Trailing edge point B2 coordinates
XC, YC, ZC: Center control coordinates
ZCU: Upper surface Z coordinate for control point
ZCL: Lower surface Z coordinate for control point

All coordinate arrays contain 960 floating-point values, representing the mesh points in the vortex lattice.

Mesh Parameters

n_sw: Number of spanwise panels (integer)
n_cw: Number of chordwise panels (integer)

Break Points

chordwise_breaks: Array defining chordwise panel break points for cranked delta wings
spanwise_breaks: Array defining spanwise panel break points for cranked delta wings

Panel Properties

panel_areas: Array of panel surface areas (960 elements)

Surface Geometry Properties

chordwise_slope_upper: Upper surface chordwise slope values
spanwise_slope_upper: Upper surface spanwise slope values
gaussian_curvature_upper: Upper surface Gaussian curvature values
chordwise_slope_lower: Lower surface chordwise slope values
spanwise_slope_lower: Lower surface spanwise slope values
gaussian_curvature_lower: Lower surface Gaussian curvature values
thickness: Panel thickness values

2. `runs` Array

The runs array contains multiple simulation runs, each representing a different test condition. Each run object includes:

Test Parameters

test_number: Integer identifying the test case
mach_number: Mach number (float, e.g., 0.3)
angle_of_attack: Angle of attack in degrees (integer, e.g., 11)
reynolds_number: Reynolds number (float, e.g., 80400000.0)
reference_pressure: Reference pressure value (float)

VLM Coefficients

vlm_lift_coefficient: Lift coefficient (float)
vlm_drag_coefficient: Drag coefficient (float)
vlm_induced_drag_coefficient: Induced drag coefficient (float)
vlm_moment_coefficient: Moment coefficient (float)
vlm_total_y_force_coefficient: Total Y-force coefficient (float)
vlm_rolling_moment_coefficient: Rolling moment coefficient (float)
vlm_scaled_rolling_moment_coefficient: Scaled rolling moment coefficient (float)
vlm_yawing_moment_coefficient: Yawing moment coefficient (float)
vlm_scaled_yawing_moment_coefficient: Scaled yawing moment coefficient (float)

Pressure and Flow Field Data

vlm_pressure_coefficient: Nested array containing pressure coefficient values
- Structure: [[cp1, cp2, ..., cp960]] (1×960 array)
- Contains pressure coefficients at each of the 960 panel control points

Velocity and Circulation

vlm_velocity_distribution: Array of velocity distribution values
vlm_circulation_distribution: Array of circulation distribution values
vlm_velocity_x_component: X-component of velocity
vlm_velocity_y_component: Y-component of velocity
vlm_velocity_z_component: Z-component of velocity

Local Flow Angles

local_angle_of_attack: Local angle of attack at each panel
local_sideslip_angle: Local sideslip angle at each panel
local_dihedral_angle: Local dihedral angle at each panel
local_orientation_angle_x: Local orientation angle (X-axis)
local_orientation_angle_y: Local orientation angle (Y-axis)
local_orientation_angle_z: Local orientation angle (Z-axis)

Additional Parameters

vlm_normalization_factors: Normalization factors used in calculations
vlm_chord_lengths: Chord lengths at each panel
vlm_pressure_coefficient_derivatives: Derivatives of pressure coefficients
vlm_scaling_factors: Scaling factors applied to various quantities
geometry_callsign: String identifier for the geometry (e.g., "020101-4TM")

Data Characteristics

Mesh Size: The vortex lattice mesh contains 960 panels (control points)
Multiple Runs: Each file typically contains 9 simulation runs with different test conditions
Coordinate System: 3D Cartesian coordinates (X, Y, Z)
Units:
- Angles: degrees
- Coordinates: length units (consistent with the geometry)
- Coefficients: dimensionless
- Pressure: pressure units (as specified by reference_pressure)

Example Usage

import json

# Load a VLM simulation result file
with open('020101-4TM.json', 'r') as f:
    data = json.load(f)

# Access geometry data
geometry = data['vlm_vd']
control_points_x = geometry['XCH']  # 960 X-coordinates
control_points_y = geometry['YCH']  # 960 Y-coordinates
control_points_z = geometry['ZCH']  # 960 Z-coordinates

# Access simulation runs
runs = data['runs']
for run in runs:
    print(f"Test {run['test_number']}: AoA={run['angle_of_attack']}°, "
          f"CL={run['vlm_lift_coefficient']:.4f}, "
          f"CD={run['vlm_drag_coefficient']:.4f}")
    
    # Access pressure coefficients (nested array)
    pressure_coeffs = run['vlm_pressure_coefficient'][0]  # 960 values

Notes

The mesh structure is consistent across all runs in a file (same vlm_vd data)
Each run represents a different flight condition (different Mach number, angle of attack, etc.)
Pressure coefficients are stored as nested arrays: [[values...]] where the outer array typically has length 1
Some arrays like vlm_velocity_distribution and vlm_circulation_distribution may be empty depending on the simulation configuration

VLM Simulation Results JSON Data Structure

Overview