Lattice-Boltzmann Method · JETcentral

Lattice-Boltzmann Method

Low-Mach cold-flow research preview. This first solver uses voxel walls and added numerical/eddy viscosity. It has no validated aircraft lift/drag or hot-jet prediction. Compare resolutions and run duration before interpreting flow features.

Side and Top views keep the freestream axis horizontal; the aircraft rotates with Conditions alpha and beta. Drag for a free view; wheel to zoom.

Load an aircraft to prepare its STL automatically, or load saved CFD results.

1. Aircraft and STL review

Loading aircraft snapshot…

Load JET JSON

Blue inlet sinks follow the actual opening outline projected onto a transverse plane, placed at least one grid cell behind the aft-most lip. Orange disks mark approximate exhaust sources. Review all boundaries; the solver uses a voxel approximation of these profiles.

2. Conditions

Airspeed/MachUnitsAlpha (deg)Beta (deg)Estimated load factorUnavailable

Load an aircraft with its official lift curve and component weights.

Atmosphere and airspeed reference

Static temperature (°F)Density (lbm/ft³)Kinematic viscosity (ft²/s)

Mach conversion uses the static temperature above (59°F by default). Compressible Euler solves density, momentum and total energy with an ideal-gas equation of state. NASA: Mach number and temperature.

Ideal bypass

Air is removed just behind each inlet and the same mass is added at its paired exhaust. Virtual plugs isolate the downstream duct/engine path. There is no engine restriction or cycle calculation. Intake demand can still cause lip spillage; excessive demand is reported or stops an unstable run.

Set total massFlow in lbm/s per pair and exitSpeed in ft/s. Zero disables that pair. Several mouths feeding one engine belong in one pair. Centers and radii below are in feet; exhaust locations use engine length as an initial estimate.

Advanced boundary JSON

Paired inlet/exhaust disks (ft, ft/s, lbm/s)

NASA Cart3D — Boundary Conditions for Simulating Propulsive Effects describes intake outflow and nozzle inflow boundaries. Our paired ideal bypass is an approximation informed by that guidance; NASA has not validated this LBM implementation.

3. Compute

Flow solverRun location

Solver, grid and run duration

Cells across longest extentTime steps

Domain padding: 0.5 aircraft extents upstream and to each side; 1.5 downstream. Alpha tilts airflow toward +Z; positive beta means wind from the right, toward -Y. The downstream boundary remains X-normal; check domain sensitivity at larger angles. Peak memory budget: 1 GiB. Under-resolved bypass disks require a finer grid. GPU selection requires the native helper and OpenCL driver; browser GPU information alone does not establish solver support.

Compute and job controls

Compute backendGPU

Local/cloud solver case and result files retain their explicit SI units.

Helper and cloud setup

Save Windows CFD Helper (.exe) — Python and solver dependencies included. Double-click to start.

Save Mac CFD Helper (.zip) — extract and double-click JETcentral CFD Helper.app. Requires Python 3.10+; first run offers NumPy setup. CPU execution.

Keep the helper window open, select Local computer, and check execution capabilities. Both launchers allow jetdesign.online, www.jetdesign.online and local previews at 127.0.0.1:8767 or localhost:8767. For other sites, add --origin with the exact origin below. GPU execution on Windows requires a native OpenCL driver.

Save Python source helper ZIP (manual setup).

Install Python 3.10+ and requirements from JETcentral/scripts/lbm-requirements.txt. In that folder run:

Enable only trusted website origins. Edge/Chrome may ask for local-network access. On the VPS, use the dedicated CFD service and authenticated CLOUD/cfd-api.php gateway; see deployment and model documentation. An unconfigured cloud gateway reports unavailable.

Ready.

4. Flow results

Surface pressure mapShow particles

Surface and particle display

Surface fieldParticle size 3.0xNumber of flow paths 50

Save particle animation

Animation formatClip duration (seconds)

Exports the current camera, aircraft, selected solved paths and cut. Video uses 20–24 frames/s; GIF uses 5 frames/s. Frames are prepared on this computer, up to 960 pixels wide. Playback speed controls the motion. No CFD rerun is needed.

Cut plane and clipping

Slice displayPlanePlane location (ft)0.500 ftExact location (ft)Slab thickness (% of axis span)5%Show cutting planeShow cutting-plane axes

Cuts affect the aircraft, particles and their tails together, including while paused. Use the XYZ arrows in the view or the exact location below. This changes the display only.

Isolate paths from an upstream window

Select solved paths by their upstream starting positions.

Filter by upstream originCenter wind Y (ft)Center wind Z (ft)Window width wind Y (ft)Window height wind Z (ft)

Wind X follows freestream; wind Y/Z define the upstream window. Only particles following paths starting inside the window are shown. Colors, particle size, playback time and zoom are preserved. Increase Number of flow paths to make more existing paths available. Cut plane settings still apply; choose Full display to see complete paths. No CFD rerun is needed.

Drag the aircraft to rotate; wheel to zoom. Enable a cut in Cut plane and clipping, then drag a colored X/Y/Z arrow to select its normal and slide that plane. Arrow keys also move a focused axis handle; Shift uses a smaller step. Surface colors sample pressure from nearby fluid cells on the voxel grid; gray faces have no sample. Particles and their short fading tails follow the final instantaneous velocity field, not time histories. Particle speed comes from the solved samples. Use Play particles to animate; Pause freezes time while rotation, camera poses, flow-path count and slicing continue to update the display. Hidden views pause automatically. Particle size is for visibility and does not represent mass flow. Check grid resolution and run duration before interpreting details.

2D flow slices

SliceField

Run summary

Iteration history

Lattice-Boltzmann Method

Download Helper

Start your local CFD helper

CFD error

Lattice-Boltzmann Method

3D display