[mgaedtke]

Hi Richard,

I’m conducting conjugate heat transfer studies during my PhD using OpenLB. Your case looks interesting, too. I’ve just send you an email.

Best,
Max

[mgaedtke]

Hi Simon,

yes, this will still work. Just check the examples/multiComponent/rayleighTaylor2d/ or 3d

Best,
Max

[mgaedtke]

Hi Manuel,

the force field in OpenLB is actually a force over reference density, thus it is equivalent to an acceleration. To convert your gravitational acceleration you can use the term

converter.getPhysDeltaT()*converter.getPhysDeltaT()/converter.getPhysDeltaX()

See you at the Spring School!

Best,
Max

[mgaedtke]

Hi Simon,

that sounds like you have implemented a buoyancy force already and the densities of oil and water differ in your initial conditions.

Best,
Max

[mgaedtke]

Hi zshi,

defining a constant pressure via the corresponding density at the outlet leads to undesired results, because in the multiphase case your density is linked to the state of your fluid.

In order to allow gas and liquid phase to leave your domain through the outlet, I suggest to define a constant velocity boundary with the flow facing outwards. The inlet should in this case be a constant pressure boundary with the pressure corresponding to the state of the influx fluid.

Cheers,
Max

[mgaedtke]

Hi zshi,

using slatticeOne.defineExteneralField ( geometry, 1, externalforcebeginat, sizeofexternalforce, f) to set additional forces when using Shan-Chen-Model is exactly right. Note that our field externalforce is actually F/rho (acceleration), so that you don’t have any problems with variing densities. Just set the externalforce to g in lattice units and you should be fine.

Cheers,
Max

[mgaedtke]

Hi mithdradates,

that depends on your definition of the coupling. If you chose to run the coupling over material 1 cells, the envelop cells will be either other cells of material number 1 or cells with other material numbers in the direct neighborhood. So, make sure, that every value and or function, that is accessed in the coupling processor, is accessible for material number 1 cells as well as boundary cells.

Best,
Max

[mgaedtke]

Hi mithdrates,

I assume you use the latest version of OpenLB, 1.3? If not, I recommend checking the latest version first.

to 1) The SC-Coupling accesses neighboring cells and calls calcRho on them. However, for boundary cells not every neighbor is a valid cell. Thus try to add the coupling procedure only on fluid cells, rather than the whole lattice. Do so by changing the line sLattice.addLatticeCoupling( coupling, sLattice ); to sLattice.addLatticeCoupling( superGeometry, 1, coupling, sLattice);. This will execute the coupling only on cells with material number 1.

to 2) If I understand correctly, what you could try is setting a constant gravitational force to the whole domain. The thermal SC-Method will then change the density for every cell according to the EOC, which will result in buoyancy. Stability with these coupled methods is not easy to achieve, I recommend to use proposed parameters from the literature first and then evolve from that to analyse the stable domain.

to 3) the sourced advection-diffusion dynamics are implemented after

Seta, T. (2013). Implicit temperature-correction-based immersed-boundary thermal lattice Boltzmann method for the simulation of natural convection. Physical Review E, 87(6), 063304.

Have a look in there for details of the source term.

Best regards,
Max

[mgaedtke]

Hi mithdradates,

to 1: we are currently preparing the release. we’re about to finalize it in the next few months.

to 2: As far as I understand your plan, yes you can it like described.

to 3: Yes, there are: for example have a look at SuperLatticePhysStrainRateFD3D

to 4: OpenLB has several convection boundaries implemented, if that is what you are looking for. To get an idea, see https://doi.org/10.4208/cicp.091009.290910s

[mgaedtke]

Hi mithdradates,

to 1: I implemented the sourced advection diffusion model by Seta (https://journals.aps.org/pre/abstract/10.1103/PhysRevE.87.063304) a few month ago and it will be included in the next release, which will become available soon.

to 2: Yes, using the temperature from the ADlattice for this purpose should be the way to go. To get an idea how to achieve this in OpenLB you can have a look at the boussinesq coupling in src/dynamics/navierStokesAdvectionDiffusionCouplingPostProcessor2D . h and .hh

Best, Max

[mgaedtke]

Hello tobit,

when you do TRT for the advection diffusion equation, make sure that omegam is the omega, which is calculated from the diffusion coefficient, and omegap is calculated with the magic parameter. For more information see http://alexkuzmin.com/wp-content/uploads/2011/05/stat_stability.pdf

I hope this will help you fix the problem.

With best regards,
Max

[mgaedtke]

Hey bujji,

have another look at the book of Krüger et. al chapter 9.1.4, where the young-laplace-test is described. Besides multi phase simulations, this test case is also valid for multi component cases.

Best regards, Max

[mgaedtke]

Hello bujji,

I suggest you to read chapter 7 in the book of Krügel et al. https://www.springer.com/de/book/9783319446479. You should find anwsers to your questions there, as we implented the converter class according to this chapter.

Best regards, Max

[mgaedtke]

Hey John,

what do you mean by condensation in combination with multiple components? What is your setup up and what is the effect you see there? Please provide some more information, so that I can reproduce your effect.

Best, Max

[mgaedtke]

Hello heng,

yes, you can use the addTemperatureBoundary() on the temperature lattice and addVelocityBoundary() on the velocity/pressure lattice for the material number indicating the inlet.

Best Regards, Max

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