OpenFOAM Case Structure and Solver Configuration скачать в хорошем качестве

OpenFOAM Case Structure and Solver Configuration

OpenFOAM is a black box to most engineers. It's not. It's just organized. A complete CFD case has three directories, each with a specific purpose. Understanding this structure is the key to running and debugging simulations. CASE DIRECTORY STRUCTURE: wrench-template/ ├── system/ (Solver settings) ├── constant/ (Physics constants, mesh) ├── 0/ (Initial and boundary conditions) ├── Allrun (Batch script) └── Allclean (Cleanup script) SYSTEM/ - The Brain: Contains dictionaries that tell OpenFOAM how to solve the equations. system/controlDict: startTime, endTime: Iteration or physical time range deltaT: Time step (for transient) or iteration step (steady-state) writeInterval: How often to save results For simpleFoam (steady state): We run 1000+ iterations until convergence. system/fvSchemes: Discretization schemes for gradients, divergence, Laplacian Example: gradSchemes { default Gauss linear; } (central differences) system/fvSolution: Solver settings for pressure, velocity (PCG, PBiCG, smoothSolver) Relaxation factors (0.3-0.7 for stability) Convergence tolerance (1e-6) system/snappyHexMeshDict: Meshing parameters (geometry, refinement levels, inflation) CONSTANT/ - The Physics: Contains mesh and properties that don't change. constant/triSurface/: wrench.stl (your geometry) constant/polyMesh/: points: Vertex coordinates faces: Cell connectivity owner: Which cell owns each face boundary: Boundary patch definitions Generated by blockMesh and snappyHexMesh. constant/transportProperties: nu (kinematic viscosity) = 1.5e-05 m²/s for air rho (density) = 1.225 kg/m³ constant/turbulenceProperties: turbulenceModel: kEpsilon (or kOmegaSST) simulationType: RAS (Reynolds-Averaged Simulation) 0/ - The Initial Conditions: The starting point for all fields. 0/p (pressure): internalField: uniform 0 (gauge pressure, relative to atmospheric) boundaryField: Conditions at inlet, outlet, walls 0/U (velocity): internalField: uniform (20 0 0) m/s (inlet velocity) boundaryField: noSlip at walls, fixedValue at inlet, zeroGradient at outlet 0/k and 0/epsilon: Turbulent kinetic energy and dissipation rate Initialized from inlet conditions Boundary conditions: turbulentIntensityKineticEnergyInlet (5%), zeroGradient at outlet POSTPROCESSING: After simulation converges, we extract: postProcessing/forceCoeffs1/0/forceCoeffs.dat: Drag coefficient (Cd) Lift coefficient (Cl) Pressure coefficient (Cp) along surface This single file the Cd value is what Dakota uses to optimize our design. THE DATA FLOW: Parameters.in (from Dakota) → wrench_parametric.py → wrench.stl → blockMesh/snappyHexMesh → simpleFoam → forceCoeffs.dat → dakota_driver.py → Results.out Each step transforms the input into the next stage's input. NEXT STEP: Tomorrow we run the simulation. We'll watch it converge, extract the drag coefficient, and celebrate our first CFD result. simpleFoam or pimpleFoam? Why choose one over the other? #OpenFOAM #CFD #Simulation #ComputationalFluidDynamics #Engineering #Solver #Day8