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March 28, 2024, 08:08 |
one-way coupled particle tracking
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#1 |
New Member
Duve Ribberink
Join Date: Mar 2024
Location: Netherlands
Posts: 5
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Hi!
I am trying to do a particle tracking using one-way coupling. Searching the forum, I found this thread discussing the same thing: Particle tracking In the thread, icoUncoupledKinematicParcelFoam is suggested as an appropriate solver. I tried to use the same method and obtained this result: Screenshot 2024-03-28 124058.jpg The figure shows the velocity magnitude of both the particle and 2-D flow. I applied a glyph filter over the particle track and made the radius scale with the velocity. There are two problems: 1. I cannot specify the 3-dimensional initial position of the particle. I did specify 3 dimensions in constant -> kinematicCloudPositions, but only the x-value seems to have any effect. 2. The straight particle track suggests fully passive transport, because I varied the density and hoped to see vertical motion. (I tried running with rho0 values matching both g/cm3 and kg/m3, but it made no difference for vertical transport). Since the particle is slowly accelerating in a somewhat uniform flow, I don't think it is a passive particle simulation as the description of the solver describes: https://www.openfoam.com/documentati...8C_source.html So my current conclusion is that the particle is somehow modelled in 1 dimension only. I don't understand why this is the case. I will include my kinematicCloudProperties file below, but I am not sure the error is in there. If anyone has a suggestion as to why my simulation behaves like this, or can direct me to other input files I should check, I will be very thankful . Code:
FoamFile { version 2.0; format ascii; class dictionary; //location "constant"; object kinematicCloudProperties; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // solution { active true; coupled false; transient yes; cellValueSourceCorrection off; maxCo 0.3; interpolationSchemes { rho cell; U cellPoint; mu cell; } integrationSchemes { U Euler; } } constantProperties { rho0 1500; youngsModulus 6e8; poissonsRatio 0.35; } subModels { particleForces { sphereDrag; gravity; } injectionModels { model1 { type manualInjection; massTotal 0; parcelBasisType fixed; nParticle 1; SOI 0; positionsFile "kinematicCloudPositions"; U0 (0 0 0); sizeDistribution { type fixedValue; fixedValueDistribution { value 0.003; } } } } dispersionModel none; patchInteractionModel none; surfaceFilmModel none; stochasticCollisionModel none; collisionModel none; pairCollisionCoeffs { // Maximum possible particle diameter expected at any time maxInteractionDistance 0.0001; writeReferredParticleCloud no; pairModel pairSpringSliderDashpot; pairSpringSliderDashpotCoeffs { useEquivalentSize no; alpha 0.12; b 1.5; mu 0.52; cohesionEnergyDensity 0; collisionResolutionSteps 12; }; wallModel wallLocalSpringSliderDashpot; wallLocalSpringSliderDashpotCoeffs { useEquivalentSize no; collisionResolutionSteps 12; upperWall { youngsModulus 1e10; poissonsRatio 0.23; alpha 0.12; b 1.5; mu 0.43; cohesionEnergyDensity 0; } lowerWall { youngsModulus 1e10; poissonsRatio 0.23; alpha 0.12; b 1.5; mu 0.43; cohesionEnergyDensity 0; } frontAndBack { youngsModulus 1e10; poissonsRatio 0.23; alpha 0.12; b 1.5; mu 0.1; cohesionEnergyDensity 0; } }; } } cloudFunctions {} |
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April 22, 2024, 09:20 |
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#2 |
New Member
Duve Ribberink
Join Date: Mar 2024
Location: Netherlands
Posts: 5
Rep Power: 2 |
Just in case anyone finds this and has the same problem, I found the problem:
I had three 'empty' boundaries, two of which were in the y-dimension to simulate 2D flow, and the final one in the z-dimension at the 'top' boundary to avoid using a 'wall' boundary and creating (unwanted) pipe-like flow. For each dimension in which at least one boundary was 'empty', the particle tracker fixed the particle in that dimension. So, the solution is having functional boundaries (non-empty) in each dimension you wish to track particle movement. I have since switched to simulating multiphase flow to more accurately represent my system, which also solves the top boundary problem. |
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