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Force Oscillations in sloshing simulation with dynamicMeshDict (6DoF) |
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thr
Join Date: Dec 2023
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Hello,
im try to simulate sloshing in a closed tank. I use OF11 and based on the tutorial sloshingTank6DoF i built up my own simulation. In the end i want the forces acting on the tank due to the liquid sloshing. When i read the data from the postProcessing folder i get really confusing Oscillations. I have no clue why this is happening. I have tried several different options in fvSchemes and fvSolution. controlDict: application foamRun; solver incompressibleVoF; startFrom latestTime; startTime 0; stopAt endTime; endTime 1; deltaT 0.0001; writeControl adjustableRunTime; writeInterval 0.1; purgeWrite 0; writeFormat binary; writePrecision 9; writeCompression off; timeFormat general; timePrecision 9; runTimeModifiable yes; adjustTimeStep yes; maxCo 0.4; maxAlphaCo 0.4; maxDeltaT 0.01; functions { forces { type forces; libs ("libforces.so"); patches ("sloshingCylinder"); log on; writeControl adjustableRunTime; writeInterval 0.001; rhoInf 1000; rho rhoInf; CofR (0.4 -0.4 0.1); // Point for calculation of moments } } fvSolution solvers { alpha.water { nAlphaCorr 1; nAlphaSubCycles 3; } "pcorr.*" { solver PCG; preconditioner { preconditioner GAMG; tolerance 1e-05; relTol 0; smoother DICGaussSeidel; cacheAgglomeration no; } tolerance 1e-05; relTol 0; maxIter 100; } p_rgh { solver GAMG; tolerance 1e-08; relTol 0.01; smoother DIC; } p_rghFinal { solver PCG; preconditioner { preconditioner GAMG; tolerance 2e-09; relTol 0; nVcycles 2; smoother DICGaussSeidel; nPreSweeps 2; } tolerance 2e-09; relTol 0; maxIter 20; } "(U|k|epsilon|omega).*" { solver smoothSolver; smoother GaussSeidel; tolerance 1e-06; relTol 0; nSweeps 1; } } PIMPLE { momentumPredictor no; nCorrectors 5; nNonOrthogonalCorrectors 1; correctPhi no; pRefPoint (0.4 -0.4 0.1); pRefValue 1e5; } relaxationFactors { equations { ".*" 1; } } dynamicMeshDict mover { type motionSolver; libs ("libfvMeshMovers.so" "libfvMotionSolvers.so"); motionSolver solidBody; select all; solidBodyMotionFunction sixDoFMotion; CofG (0.4 -0.4 0.1); translationRotation table; //interpolationScheme spline; file "$FOAM_CASE/constant/6DoF.dat"; } 6DoF.dat is a table with a frequency of 800hz. simple acceleration in x direction with 9.81m/s^2. I have attached a plot of the force. Its the same for Fx,Fy,Fz. Every 10nth data point drops. The sloshing in Paraview look good. I think this could be a problem with the dynamictMeshDict, the forcesFunction or the adjustableTimeStep. Best, T |
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