Can we define boundary nodes in the
advection-diffusion lattice in the same manner as
the NS lattice? My NS lattice has a porous
structure (defined by bounce back nodes)
I’m not sur what would represent to do bounceback on wall nodes for the temperature… (If I understand that’s what you are trying to do…). But you still can define walls with fixed temperature the same way as you do for fluids (see lines 72-73 of the rayleigh_benard3d.cpp file).
How is the coupling between the two lattices
achieved? I dont quite understand the
“dir.push_back” vector. Does this simply state
that the flow is in the x direction
This only states the direction of the force. It can be in any drection a-priori. Here the choice was to make it in the z direction.
What does converter.T0 return? and if I do not
want to include gravity as a force can I simply
set it to zero?
The converter is used to convert from lb units to physical ones by using the two dimensional numbers (Rayleigh and Prandtl numbers). The Ra number is defined with respect to a temperature difference. Therefore T0 is the “cold” temperature…
For the typical numbers we use, they are around 3000-10000 for the Rayleigh (but can be a lot bigger) Pr~1 (air is 0.73 and water is 4 if i remember correctly) and delta T <0.001.
Also, can I use the AdvectionDiffusion lattice structure to simulate the transport of a passive scalar? In this case instead of a temperature gradient, I will have a concentration gradient, but I will need to do bounce-back for the scalar. Is this possible? If not, I was planning to write a routine that takes the flow field from OpenLB and combines it with Random Walk statistics (to account for diffusivity) to model the flow of a passive scalar.
That’s exactly what you have to do. But don’t forget that probably you will have corners also…
Also, can I use the AdvectionDiffusion lattice
structure to simulate the transport of a passive
scalar? In this case instead of a temperature
gradient, I will have a concentration gradient,
but I will need to do bounce-back for the scalar.
Is this possible?
You may have to add a new coupling post processor do so, because by default the advection diffusion also acts on the navier stokes solver. And therefore it is not a passive scalar anymore…
Not sure I understand how to set the corners for an interior node. The interior nodes are the solid parts of my porous media, so how do I distinguish between the NNN, NNP corners?
I’ve been trying to find the part of the code that does the coupling between the advection diffusion lattice and the NS lattice. Could you point me to the location, so that I can create a new coupling post processor based on it?
Also, would the transport of a passive scalar be part of a future release of OpenLB? Perhaps I can help in coding it.