Mamin
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MaminMember
The charR is not mentioned in the user documentation at all. So it is hard to get info from there. And I’m not requesting a complete intro, I will come for to the spring school for that but some hints will help people to continue their projects and keep using openLB.
ThanksMaminMemberThanks for answering. Since I can’t set a pressure boundary at the inlet and out let as well. I ran NavierStokes on Comsol for the same system and place the pressure boundaries at the inlet and outlet then obtained the velocity at the inlet and add as boundary condition in openLB. However, I obtained much lower pressure at the inlet.
Maybe it is not a good idea but I know that LBM should converge to NS at the continuum regime. However, there is something missing here.MaminMemberI have 0 pressure at the outlet. Thanks
MaminMemberHi mgaedtke,
I have defined the charRho as the density of helium at 100 Pascal (0.00016). However, what I get at the inlet is a pressure of 10 Pascal instead (U=15 m/s, charNu=0.12). I was expecting to get 100 Pascal at the inlet. Any hint?
ThanksMaminMemberI looked at the examples. However, they always assume zero pressure at the outlet. I’m planning to attend the spring school but I can’t just wait 6 month to run the simulations.
Thank youMaminMemberThank you very much. Do you know if openLB model compressible fluid?
MaminMemberThank you. Would you please explain why it won’t work? I’m new to the method but since I could do that in NavierStokes I want to know how to make similar system in LB in order to benchmark.
(Since LB should converge to NavierStokes in the continuum regime)Thanks again
MaminMemberI realized that this happened whrn I replaced
bc.addVelocityBoundary( superGeometry, 3, omega );
with:
bc.addPressureBoundary( superGeometry, 3, omega );
sLattice.defineRhoU( superGeometry, 3, rho, u );for the inflow boundary condition.
Do you know why this happens? I thought I can choose velocity or pressure as boundary conditions.
ThanksMaminMemberI want to simulate a gas (helium) in a aerodynamic lens (or just a cylinder of 1 cm radius) with smaller outlet (1mm). The pressure at the inflow is 2 mbar and 0 on the outflow.
Thank youMaminMemberSorry the figure just missed up. they are just 4 cylinders connected to each other with different radii. r1r2r3r4 where r1=r3 and they are greater than r2 and r4.
ThanksMaminMemberThanks Mathias,
I tried to build the following figure using 4 cylinders
______ _______
__ ___
___ ___
______ _______IndicatorCylinder3D<T> inflow( C0, C1, radius1 );
IndicatorCylinder3D<T> cyl1( C1, C2, radius1 );
IndicatorCylinder3D<T> cyl2( C2, C3, radius2 );
IndicatorCylinder3D<T> cyl3( C3, C4, radius1 );
IndicatorCylinder3D<T> cyl4( C4, C5, radius3 );
IndicatorCylinder3D<T> outflow( C5, C6, radius3 );
The geometry preparation went OK. However, I got segmentation fault:[prepareGeometry] Prepare Geometry … OK
[prepareLattice] Prepare Lattice …
[prepareLattice] Prepare Lattice … OK
[Timer] step=0; percent=0; passedTime=0.502; remTime=1.004e+07; MLUPs=0
[LatticeStatistics] step=0; t=0; uMax=0; avEnergy=0; avRho=1
[Timer] step=0; percent=0; passedTime=0.967; remTime=1.934e+07; MLUPs=0
[LatticeStatistics] step=0; t=0; uMax=0; avEnergy=nan; avRho=nan
Segmentation fault: 11
I’m trying to figure what I did wrong.
Thanks 
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