[lsflbm]

Dear Nicolas,

Thank you for answering my question.

However, I just start leaning LBM and Openlb for not a long time and I couldn’t really get the point of what you said. Could you plz tell me more details? Do you mean that the rectangular poiseuille flow is a particle-free flow? What else could I do besides confirming the CFL condition?

Thank you!

Best,
Evan

[lsflbm]

Dear Jan,
I tried to set the lattice velocity to 1/10 but it didn’t work, it still goes quite large at about 10% of the whole time as before. Besides, I didn’t add gravity in this model. It’s just a sphere particle in a rectangular channel with rectangular poiseuille flow.
In addition, I have a lilttle problem of what you mentioned that change the particle’s position before the coupling from the particle to the fluid via couple_particles_to_lattice. Did you mean change the position after couple_lattice_to_particles and before the couple_particles_to_lattice ? I seperate the execute to couple lattice, change postion, couple patcicle. But it still couldn’t work. Could you tell me more details?

Thank you again for answering me!

Best,
Evan

[lsflbm]

Dear Jan,
Thank you for giving suggestion! I tried the method you mention. However, when running the programm, something goes wrong.
I use the settlingCube3d example and add a rectangular poiseuille flow. The particle is a sphere particle. At the firsi time, the programm goes very well. However, at about 5400 step ,the avEnergy and avRho become -nan ,and a few steps later, the position and velocity become very big, like this.
[Timer] step=4800; percent=8; passedTime=306.526; remTime=3525.05; MLUPs=13.9401
[LatticeStatistics] step=4800; t=0.0008; uMax=0.132613; avEnergy=0.000586339; avRho=1.04953
[ParticleInfo] Particle 0
[ParticleInfo] |Circum radius(m)= 1.58333e-05
[ParticleInfo] |Mass(kg)= 1.4844e-11
[ParticleInfo] |Position(m)= ( 0.000326169, 2.5e-05, 5e-05)
[ParticleInfo] |Angle(°)= ( -2.17393e-12, -2.33405e-12, -1.51876e-11)
[ParticleInfo] |Velocity(m/s)= ( 1.33061, 1.60779e-16, -5.15718e-15)
[ParticleInfo] |Ang. Velocity(°/s)= ( 8.12674e-08, 2.37697e-09, 5.95079e-07)
[ParticleInfo] |Force(N)= ( 4.93697e-09, -6.73433e-18, 6.7951e-20)
[ParticleInfo] |Acceleration(m/s^2)= ( 332.59, -4.53673e-07, 4.57767e-09)
[ParticleInfo] |Ang. acc.(°/s^2)= ( -0.124323, 0.0334074, 6.40006)
[setBoundaryValues] step=4830; maxVel=0.137543
[setBoundaryValues] step=4860; maxVel=0.139692
[setBoundaryValues] step=4890; maxVel=0.141859
[setBoundaryValues] step=4920; maxVel=0.144042
[setBoundaryValues] step=4950; maxVel=0.146242
[Timer] step=4950; percent=8.25; passedTime=314.503; remTime=3497.65; MLUPs=13.9995
[LatticeStatistics] step=4950; t=0.000825; uMax=0.143308; avEnergy=0.000719076; avRho=1.05481
[ParticleInfo] Particle 0
[ParticleInfo] |Circum radius(m)= 1.58333e-05
[ParticleInfo] |Mass(kg)= 1.4844e-11
[ParticleInfo] |Position(m)= ( 0.000360634, 2.5e-05, 5e-05)
[ParticleInfo] |Angle(°)= ( 7.30257e-13, -2.50328e-12, 1.41442e-11)
[ParticleInfo] |Velocity(m/s)= ( 1.43133, -5.47747e-13, -4.41999e-15)
[ParticleInfo] |Ang. Velocity(°/s)= ( 1.68225e-07, -2.077e-09, 5.91022e-06)
[ParticleInfo] |Force(N)= ( 1.4875e-07, 1.01319e-17, 4.42079e-20)
[ParticleInfo] |Acceleration(m/s^2)= ( 10020.8, 6.82556e-07, 2.97816e-09)
[ParticleInfo] |Ang. acc.(°/s^2)= ( 0.350576, 0.0311973, 27.0941)
[setBoundaryValues] step=4980; maxVel=0.148459
[setBoundaryValues] step=5010; maxVel=0.150692
[setBoundaryValues] step=5040; maxVel=0.152942
[setBoundaryValues] step=5070; maxVel=0.155208
[setBoundaryValues] step=5100; maxVel=0.157491
[Timer] step=5100; percent=8.5; passedTime=322.481; remTime=3471.41; MLUPs=13.996
[LatticeStatistics] step=5100; t=0.00085; uMax=0.154416; avEnergy=0.00087751; avRho=1.06037
[ParticleInfo] Particle 0
[ParticleInfo] |Circum radius(m)= 1.58333e-05
[ParticleInfo] |Mass(kg)= 1.4844e-11
[ParticleInfo] |Position(m)= ( 0.000397766, 2.5e-05, 5e-05)
[ParticleInfo] |Angle(°)= ( 2.53597e-12, -2.56859e-12, 5.61068e-11)
[ParticleInfo] |Velocity(m/s)= ( 1.54258, -8.64617e-13, -5.10585e-15)
[ParticleInfo] |Ang. Velocity(°/s)= ( -7.01492e-09, -2.54223e-10, 4.43621e-06)
[ParticleInfo] |Force(N)= ( -4.12592e-10, 7.68024e-17, -1.13703e-19)
[ParticleInfo] |Acceleration(m/s^2)= ( -27.7951, 5.17396e-06, -7.65988e-09)
[ParticleInfo] |Ang. acc.(°/s^2)= ( 1.17213, 0.133466, 55.016)
[setBoundaryValues] step=5130; maxVel=0.159789
[setBoundaryValues] step=5160; maxVel=0.162104
[setBoundaryValues] step=5190; maxVel=0.164436
[setBoundaryValues] step=5220; maxVel=0.166783
[setBoundaryValues] step=5250; maxVel=0.169146
[Timer] step=5250; percent=8.75; passedTime=330.475; remTime=3446.38; MLUPs=13.9698
[LatticeStatistics] step=5250; t=0.000875; uMax=19.5993; avEnergy=-nan; avRho=-nan
[ParticleInfo] Particle 0
[ParticleInfo] |Circum radius(m)= 1.58333e-05
[ParticleInfo] |Mass(kg)= 1.4844e-11
[ParticleInfo] |Position(m)= ( 0.000437653, 2.5e-05, 5e-05)
[ParticleInfo] |Angle(°)= ( -1.33142e-11, -3.37498e-12, 1.37863e-10)
[ParticleInfo] |Velocity(m/s)= ( 1.65302, -1.17893e-12, -1.10465e-14)
[ParticleInfo] |Ang. Velocity(°/s)= ( -7.76043e-07, -1.06017e-07, 0.000170989)
[ParticleInfo] |Force(N)= ( 4.56389e-08, 2.52804e-16, 2.18143e-19)
[ParticleInfo] |Acceleration(m/s^2)= ( 3074.56, 1.70307e-05, 1.46957e-08)
[ParticleInfo] |Ang. acc.(°/s^2)= ( 2.65106, 0.646281, -253.488)
[setBoundaryValues] step=5280; maxVel=0.171525
[setBoundaryValues] step=5310; maxVel=0.17392
[setBoundaryValues] step=5340; maxVel=0.176331
[setBoundaryValues] step=5370; maxVel=0.178758
[setBoundaryValues] step=5400; maxVel=0.1812
[Timer] step=5400; percent=9; passedTime=338.417; remTime=3421.77; MLUPs=14.0595
[LatticeStatistics] step=5400; t=0.0009; uMax=120.978; avEnergy=-nan; avRho=-nan
[ParticleInfo] Particle 0
[ParticleInfo] |Circum radius(m)= 1.58333e-05
[ParticleInfo] |Mass(kg)= 1.4844e-11
[ParticleInfo] |Position(m)= ( 0.000480408, 2.5e-05, 5e-05)
[ParticleInfo] |Angle(°)= ( -1.44732e-10, -5.16732e-12, 1.76828e-09)
[ParticleInfo] |Velocity(m/s)= ( 1.76688, 6.3939e-11, -1.72505e-14)
[ParticleInfo] |Ang. Velocity(°/s)= ( -1.64761e-05, 6.05737e-08, 0.000779846)
[ParticleInfo] |Force(N)= ( 1.11817e-08, 6.74486e-15, 1.56529e-18)
[ParticleInfo] |Acceleration(m/s^2)= ( 753.279, 0.000454382, 1.05449e-07)
[ParticleInfo] |Ang. acc.(°/s^2)= ( -47.1061, 2.13715, -6333.05)
[setBoundaryValues] step=5430; maxVel=0.183658
[setBoundaryValues] step=5460; maxVel=0.186131
[setBoundaryValues] step=5490; maxVel=0.18862
[setBoundaryValues] step=5520; maxVel=0.191124
[setBoundaryValues] step=5550; maxVel=0.193643
[Timer] step=5550; percent=9.25; passedTime=346.566; remTime=3400.09; MLUPs=13.7041
[LatticeStatistics] step=5550; t=0.000925; uMax=276.399; avEnergy=-nan; avRho=-nan
[ParticleInfo] Particle 0
[ParticleInfo] |Circum radius(m)= 1.58333e-05
[ParticleInfo] |Mass(kg)= 1.4844e-11
[ParticleInfo] |Position(m)= ( 0.00052615, 2.5e-05, 5e-05)
[ParticleInfo] |Angle(°)= ( -4.25498e-10, -1.66612e-12, 7.73915e-09)
[ParticleInfo] |Velocity(m/s)= ( 1.89098, 1.05054e-11, -3.86624e-14)
[ParticleInfo] |Ang. Velocity(°/s)= ( -3.72311e-05, 1.88295e-06, -0.0041353)
[ParticleInfo] |Force(N)= ( 7.07657e-08, 1.0805e-14, -3.10701e-18)
[ParticleInfo] |Acceleration(m/s^2)= ( 4767.28, 0.000727903, -2.09311e-07)
[ParticleInfo] |Ang. acc.(°/s^2)= ( -107.366, 2.11181, -15422.1)
[setBoundaryValues] step=5580; maxVel=0.196177
[setBoundaryValues] step=5610; maxVel=0.198726
[setBoundaryValues] step=5640; maxVel=0.201291
[setBoundaryValues] step=5670; maxVel=0.20387
[setBoundaryValues] step=5700; maxVel=0.206464
[Timer] step=5700; percent=9.5; passedTime=354.433; remTime=3376.44; MLUPs=14.1953
[LatticeStatistics] step=5700; t=0.00095; uMax=63.6949; avEnergy=-nan; avRho=-nan
[ParticleInfo] Particle 0
[ParticleInfo] |Circum radius(m)= 1.58333e-05
[ParticleInfo] |Mass(kg)= 1.4844e-11
[ParticleInfo] |Position(m)= ( 0.000574989, 2.5e-05, 5e-05)
[ParticleInfo] |Angle(°)= ( -1.0073e-09, -1.77059e-10, 5.05713e-08)
[ParticleInfo] |Velocity(m/s)= ( 2.02149, 1.17921e-09, 2.1672e-13)
[ParticleInfo] |Ang. Velocity(°/s)= ( -1.23342e-05, -2.12496e-05, -0.00623013)
[ParticleInfo] |Force(N)= ( 2.03958e-07, -5.41757e-14, -1.14054e-17)
[ParticleInfo] |Acceleration(m/s^2)= ( 13740.1, -0.00364966, -7.68349e-07)
[ParticleInfo] |Ang. acc.(°/s^2)= ( -261.488, -2.67581, 11448.6)
[setBoundaryValues] step=5730; maxVel=0.209073
[setBoundaryValues] step=5760; maxVel=0.211696
[setBoundaryValues] step=5790; maxVel=0.214334
[setBoundaryValues] step=5820; maxVel=0.216986
[setBoundaryValues] step=5850; maxVel=0.219652
[Timer] step=5850; percent=9.75; passedTime=362.293; remTime=3353.53; MLUPs=14.2061
[LatticeStatistics] step=5850; t=0.000975; uMax=23106.1; avEnergy=-nan; avRho=-nan
[ParticleInfo] Particle 0
[ParticleInfo] |Circum radius(m)= 1.58333e-05
[ParticleInfo] |Mass(kg)= 1.4844e-11
[ParticleInfo] |Position(m)= ( 1.09741e+41, 2.5e-05, 5e-05)
[ParticleInfo] |Angle(°)= ( 26.2179, -14.427, 50.8281)
[ParticleInfo] |Velocity(m/s)= ( 4.11529e+46, -1.39122e+41, -9.36546e+38)
[ParticleInfo] |Ang. Velocity(°/s)= ( 3.13484e+42, -7.97655e+45, 1.18674e+48)
[ParticleInfo] |Force(N)= ( 0, 0, 0)
[ParticleInfo] |Acceleration(m/s^2)= ( 0, 0, 0)
[ParticleInfo] |Ang. acc.(°/s^2)= ( 0, 0, 0)
[setBoundaryValues] step=5880; maxVel=0.222333
[setBoundaryValues] step=5910; maxVel=0.225028
[setBoundaryValues] step=5940; maxVel=0.227737
[setBoundaryValues] step=5970; maxVel=0.23046
[setBoundaryValues] step=6000; maxVel=0.233196

Could you plz tell me what’s going on?

Best
Evan

[lsflbm]

Dear Nicolas,

Thank you for answering my question!I have already update to v 1.5 and read the new cpp.

I have an idea that I think may work this well. When I want the particle to moving along x-axis,I can reset the particle’s velocity in y and z-axis to 0 before the collide and stream step. Therefore, when the particle is about to move, it only has the velcity in x-axis. Will my idea work? Could the fuction setVelToAnalyticalVel (AnalyticalConst3D< T, T > &) useful to this?

Best,
Evan

[lsflbm]

Dear Nicolas,

Thank you for answering my question!I have already update to v 1.5 and read the new cpp.

I have an idea that I think may work this well. When I want the particle to moving along x-axis,I can reset the particle’s velocity in y and z-axis to 0 before the collide and stream step. Therefore, when the particle is about to move, it only has the velcity in x-axis. Will my idea work? Could the fuction setVelToAnalyticalVel (AnalyticalConst3D< T, T > &) useful to this?

Best,
Evan

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